postgresql/src/backend/postmaster/pgstat.c

6375 lines
169 KiB
C
Raw Normal View History

/* ----------
* pgstat.c
*
* All the statistics collector stuff hacked up in one big, ugly file.
*
* TODO: - Separate collector, postmaster and backend stuff
* into different files.
*
* - Add some automatic call for pgstat vacuuming.
*
* - Add a pgstat config column to pg_database, so this
* entire thing can be enabled/disabled on a per db basis.
*
* Copyright (c) 2001-2018, PostgreSQL Global Development Group
*
2010-09-20 22:08:53 +02:00
* src/backend/postmaster/pgstat.c
* ----------
*/
2001-06-30 21:01:27 +02:00
#include "postgres.h"
#include <unistd.h>
#include <fcntl.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <time.h>
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#include "pgstat.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/transam.h"
#include "access/twophase_rmgr.h"
#include "access/xact.h"
#include "catalog/pg_database.h"
#include "catalog/pg_proc.h"
#include "common/ip.h"
#include "libpq/libpq.h"
#include "libpq/pqsignal.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "pg_trace.h"
#include "postmaster/autovacuum.h"
#include "postmaster/fork_process.h"
#include "postmaster/postmaster.h"
#include "replication/walsender.h"
#include "storage/backendid.h"
#include "storage/dsm.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/lmgr.h"
#include "storage/pg_shmem.h"
#include "storage/procsignal.h"
#include "storage/sinvaladt.h"
#include "utils/ascii.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"
#include "utils/timestamp.h"
#include "utils/tqual.h"
/* ----------
* Timer definitions.
* ----------
*/
Phase 2 of pgindent updates. Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-06-21 21:18:54 +02:00
#define PGSTAT_STAT_INTERVAL 500 /* Minimum time between stats file
* updates; in milliseconds. */
Phase 2 of pgindent updates. Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-06-21 21:18:54 +02:00
#define PGSTAT_RETRY_DELAY 10 /* How long to wait between checks for a
* new file; in milliseconds. */
#define PGSTAT_MAX_WAIT_TIME 10000 /* Maximum time to wait for a stats
* file update; in milliseconds. */
Phase 2 of pgindent updates. Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-06-21 21:18:54 +02:00
#define PGSTAT_INQ_INTERVAL 640 /* How often to ping the collector for a
* new file; in milliseconds. */
Phase 2 of pgindent updates. Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-06-21 21:18:54 +02:00
#define PGSTAT_RESTART_INTERVAL 60 /* How often to attempt to restart a
* failed statistics collector; in
* seconds. */
#define PGSTAT_POLL_LOOP_COUNT (PGSTAT_MAX_WAIT_TIME / PGSTAT_RETRY_DELAY)
#define PGSTAT_INQ_LOOP_COUNT (PGSTAT_INQ_INTERVAL / PGSTAT_RETRY_DELAY)
Try to ensure that stats collector's receive buffer size is at least 100KB. Since commit 4e37b3e15, buildfarm member frogmouth has been failing occasionally with symptoms indicating that some expected stats data is getting dropped. The reason that that commit changed the behavior seems probably to be that more data is getting shoved at the collector in a short span of time. In current sources, the stats test's first session sends about 9KB of data while exiting, which is probably the same as what was sent just before wait_for_stats() in the previous test design. But now, the test's second session is starting up concurrently, and it sends another 2KB (presumably reflecting its initial catalog accesses). Since frogmouth is running on Windows XP, which reputedly has a default socket receive buffer size of only 8KB, it is not very surprising if this has put us over the threshold where the receive buffer can overflow and drop messages. The same mechanism could very easily explain the intermittent stats test failures we've been seeing for years, since background processes such as the bgwriter will sometimes send data concurrently with all this, and could thus cause occasional buffer overflows. Hence, insert some code into pgstat_init() to increase the stats socket's receive buffer size to 100KB if it's less than that. (On failure, emit a LOG message, but keep going.) Modern systems seem to have default sizes in the range of 100KB-250KB, but older platforms don't. I couldn't find any platforms that wouldn't accept 100KB, so in theory this won't cause any portability problems. If this is successful at reducing the buildfarm failure rate in HEAD, we should back-patch it, because it's certain that similar buffer overflows happen in the field on platforms with small buffer sizes. Going forward, there might be an argument for trying to increase the buffer size even more, but let's take a baby step first. Discussion: https://postgr.es/m/22173.1494788088@sss.pgh.pa.us
2017-05-16 21:24:52 +02:00
/* Minimum receive buffer size for the collector's socket. */
#define PGSTAT_MIN_RCVBUF (100 * 1024)
/* ----------
* The initial size hints for the hash tables used in the collector.
* ----------
*/
#define PGSTAT_DB_HASH_SIZE 16
#define PGSTAT_TAB_HASH_SIZE 512
#define PGSTAT_FUNCTION_HASH_SIZE 512
/* ----------
* Total number of backends including auxiliary
*
* We reserve a slot for each possible BackendId, plus one for each
* possible auxiliary process type. (This scheme assumes there is not
* more than one of any auxiliary process type at a time.) MaxBackends
* includes autovacuum workers and background workers as well.
* ----------
*/
#define NumBackendStatSlots (MaxBackends + NUM_AUXPROCTYPES)
/* ----------
* GUC parameters
* ----------
*/
bool pgstat_track_activities = false;
bool pgstat_track_counts = false;
int pgstat_track_functions = TRACK_FUNC_OFF;
int pgstat_track_activity_query_size = 1024;
/* ----------
* Built from GUC parameter
* ----------
*/
char *pgstat_stat_directory = NULL;
char *pgstat_stat_filename = NULL;
char *pgstat_stat_tmpname = NULL;
/*
* BgWriter global statistics counters (unused in other processes).
* Stored directly in a stats message structure so it can be sent
* without needing to copy things around. We assume this inits to zeroes.
*/
PgStat_MsgBgWriter BgWriterStats;
/* ----------
* Local data
* ----------
*/
NON_EXEC_STATIC pgsocket pgStatSock = PGINVALID_SOCKET;
static struct sockaddr_storage pgStatAddr;
static time_t last_pgstat_start_time;
static bool pgStatRunningInCollector = false;
/*
* Structures in which backends store per-table info that's waiting to be
* sent to the collector.
*
* NOTE: once allocated, TabStatusArray structures are never moved or deleted
* for the life of the backend. Also, we zero out the t_id fields of the
* contained PgStat_TableStatus structs whenever they are not actively in use.
* This allows relcache pgstat_info pointers to be treated as long-lived data,
* avoiding repeated searches in pgstat_initstats() when a relation is
* repeatedly opened during a transaction.
*/
2007-11-15 22:14:46 +01:00
#define TABSTAT_QUANTUM 100 /* we alloc this many at a time */
typedef struct TabStatusArray
{
struct TabStatusArray *tsa_next; /* link to next array, if any */
2007-11-15 22:14:46 +01:00
int tsa_used; /* # entries currently used */
PgStat_TableStatus tsa_entries[TABSTAT_QUANTUM]; /* per-table data */
} TabStatusArray;
static TabStatusArray *pgStatTabList = NULL;
2003-08-04 02:43:34 +02:00
/*
* pgStatTabHash entry: map from relation OID to PgStat_TableStatus pointer
*/
typedef struct TabStatHashEntry
{
Oid t_id;
PgStat_TableStatus *tsa_entry;
} TabStatHashEntry;
/*
* Hash table for O(1) t_id -> tsa_entry lookup
*/
static HTAB *pgStatTabHash = NULL;
/*
* Backends store per-function info that's waiting to be sent to the collector
* in this hash table (indexed by function OID).
*/
static HTAB *pgStatFunctions = NULL;
/*
* Indicates if backend has some function stats that it hasn't yet
* sent to the collector.
*/
static bool have_function_stats = false;
/*
* Tuple insertion/deletion counts for an open transaction can't be propagated
* into PgStat_TableStatus counters until we know if it is going to commit
* or abort. Hence, we keep these counts in per-subxact structs that live
* in TopTransactionContext. This data structure is designed on the assumption
* that subxacts won't usually modify very many tables.
*/
typedef struct PgStat_SubXactStatus
{
2007-11-15 22:14:46 +01:00
int nest_level; /* subtransaction nest level */
struct PgStat_SubXactStatus *prev; /* higher-level subxact if any */
Phase 2 of pgindent updates. Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-06-21 21:18:54 +02:00
PgStat_TableXactStatus *first; /* head of list for this subxact */
} PgStat_SubXactStatus;
static PgStat_SubXactStatus *pgStatXactStack = NULL;
static int pgStatXactCommit = 0;
static int pgStatXactRollback = 0;
PgStat_Counter pgStatBlockReadTime = 0;
PgStat_Counter pgStatBlockWriteTime = 0;
/* Record that's written to 2PC state file when pgstat state is persisted */
typedef struct TwoPhasePgStatRecord
{
Phase 2 of pgindent updates. Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-06-21 21:18:54 +02:00
PgStat_Counter tuples_inserted; /* tuples inserted in xact */
PgStat_Counter tuples_updated; /* tuples updated in xact */
PgStat_Counter tuples_deleted; /* tuples deleted in xact */
PgStat_Counter inserted_pre_trunc; /* tuples inserted prior to truncate */
PgStat_Counter updated_pre_trunc; /* tuples updated prior to truncate */
PgStat_Counter deleted_pre_trunc; /* tuples deleted prior to truncate */
2007-11-15 22:14:46 +01:00
Oid t_id; /* table's OID */
bool t_shared; /* is it a shared catalog? */
bool t_truncated; /* was the relation truncated? */
} TwoPhasePgStatRecord;
/*
* Info about current "snapshot" of stats file
*/
static MemoryContext pgStatLocalContext = NULL;
static HTAB *pgStatDBHash = NULL;
/* Status for backends including auxiliary */
static LocalPgBackendStatus *localBackendStatusTable = NULL;
/* Total number of backends including auxiliary */
static int localNumBackends = 0;
/*
* Cluster wide statistics, kept in the stats collector.
* Contains statistics that are not collected per database
* or per table.
*/
static PgStat_ArchiverStats archiverStats;
static PgStat_GlobalStats globalStats;
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
/*
* List of OIDs of databases we need to write out. If an entry is InvalidOid,
* it means to write only the shared-catalog stats ("DB 0"); otherwise, we
* will write both that DB's data and the shared stats.
*/
static List *pending_write_requests = NIL;
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
/* Signal handler flags */
2006-10-04 02:30:14 +02:00
static volatile bool need_exit = false;
static volatile bool got_SIGHUP = false;
/*
* Total time charged to functions so far in the current backend.
* We use this to help separate "self" and "other" time charges.
* (We assume this initializes to zero.)
*/
static instr_time total_func_time;
/* ----------
* Local function forward declarations
* ----------
*/
#ifdef EXEC_BACKEND
static pid_t pgstat_forkexec(void);
#endif
NON_EXEC_STATIC void PgstatCollectorMain(int argc, char *argv[]) pg_attribute_noreturn();
static void pgstat_exit(SIGNAL_ARGS);
static void pgstat_beshutdown_hook(int code, Datum arg);
static void pgstat_sighup_handler(SIGNAL_ARGS);
static PgStat_StatDBEntry *pgstat_get_db_entry(Oid databaseid, bool create);
static PgStat_StatTabEntry *pgstat_get_tab_entry(PgStat_StatDBEntry *dbentry,
2010-02-26 03:01:40 +01:00
Oid tableoid, bool create);
static void pgstat_write_statsfiles(bool permanent, bool allDbs);
static void pgstat_write_db_statsfile(PgStat_StatDBEntry *dbentry, bool permanent);
static HTAB *pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep);
static void pgstat_read_db_statsfile(Oid databaseid, HTAB *tabhash, HTAB *funchash, bool permanent);
static void backend_read_statsfile(void);
static void pgstat_read_current_status(void);
static bool pgstat_write_statsfile_needed(void);
static bool pgstat_db_requested(Oid databaseid);
static void pgstat_send_tabstat(PgStat_MsgTabstat *tsmsg);
static void pgstat_send_funcstats(void);
static HTAB *pgstat_collect_oids(Oid catalogid);
static PgStat_TableStatus *get_tabstat_entry(Oid rel_id, bool isshared);
static void pgstat_setup_memcxt(void);
static const char *pgstat_get_wait_activity(WaitEventActivity w);
static const char *pgstat_get_wait_client(WaitEventClient w);
static const char *pgstat_get_wait_ipc(WaitEventIPC w);
static const char *pgstat_get_wait_timeout(WaitEventTimeout w);
static const char *pgstat_get_wait_io(WaitEventIO w);
static void pgstat_setheader(PgStat_MsgHdr *hdr, StatMsgType mtype);
static void pgstat_send(void *msg, int len);
static void pgstat_recv_inquiry(PgStat_MsgInquiry *msg, int len);
static void pgstat_recv_tabstat(PgStat_MsgTabstat *msg, int len);
static void pgstat_recv_tabpurge(PgStat_MsgTabpurge *msg, int len);
static void pgstat_recv_dropdb(PgStat_MsgDropdb *msg, int len);
static void pgstat_recv_resetcounter(PgStat_MsgResetcounter *msg, int len);
static void pgstat_recv_resetsharedcounter(PgStat_MsgResetsharedcounter *msg, int len);
static void pgstat_recv_resetsinglecounter(PgStat_MsgResetsinglecounter *msg, int len);
static void pgstat_recv_autovac(PgStat_MsgAutovacStart *msg, int len);
static void pgstat_recv_vacuum(PgStat_MsgVacuum *msg, int len);
static void pgstat_recv_analyze(PgStat_MsgAnalyze *msg, int len);
static void pgstat_recv_archiver(PgStat_MsgArchiver *msg, int len);
static void pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len);
static void pgstat_recv_funcstat(PgStat_MsgFuncstat *msg, int len);
static void pgstat_recv_funcpurge(PgStat_MsgFuncpurge *msg, int len);
static void pgstat_recv_recoveryconflict(PgStat_MsgRecoveryConflict *msg, int len);
static void pgstat_recv_deadlock(PgStat_MsgDeadlock *msg, int len);
static void pgstat_recv_tempfile(PgStat_MsgTempFile *msg, int len);
/* ------------------------------------------------------------
* Public functions called from postmaster follow
* ------------------------------------------------------------
*/
/* ----------
* pgstat_init() -
*
* Called from postmaster at startup. Create the resources required
* by the statistics collector process. If unable to do so, do not
* fail --- better to let the postmaster start with stats collection
* disabled.
* ----------
*/
void
pgstat_init(void)
{
2003-08-04 02:43:34 +02:00
ACCEPT_TYPE_ARG3 alen;
struct addrinfo *addrs = NULL,
*addr,
hints;
int ret;
2004-08-29 07:07:03 +02:00
fd_set rset;
struct timeval tv;
2004-08-29 07:07:03 +02:00
char test_byte;
int sel_res;
int tries = 0;
2006-10-04 02:30:14 +02:00
#define TESTBYTEVAL ((char) 199)
/*
* This static assertion verifies that we didn't mess up the calculations
* involved in selecting maximum payload sizes for our UDP messages.
* Because the only consequence of overrunning PGSTAT_MAX_MSG_SIZE would
* be silent performance loss from fragmentation, it seems worth having a
* compile-time cross-check that we didn't.
*/
StaticAssertStmt(sizeof(PgStat_Msg) <= PGSTAT_MAX_MSG_SIZE,
"maximum stats message size exceeds PGSTAT_MAX_MSG_SIZE");
/*
* Create the UDP socket for sending and receiving statistic messages
*/
hints.ai_flags = AI_PASSIVE;
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = 0;
hints.ai_addrlen = 0;
hints.ai_addr = NULL;
hints.ai_canonname = NULL;
hints.ai_next = NULL;
ret = pg_getaddrinfo_all("localhost", NULL, &hints, &addrs);
if (ret || !addrs)
{
ereport(LOG,
(errmsg("could not resolve \"localhost\": %s",
gai_strerror(ret))));
goto startup_failed;
}
2003-08-04 02:43:34 +02:00
/*
* On some platforms, pg_getaddrinfo_all() may return multiple addresses
* only one of which will actually work (eg, both IPv6 and IPv4 addresses
* when kernel will reject IPv6). Worse, the failure may occur at the
* bind() or perhaps even connect() stage. So we must loop through the
* results till we find a working combination. We will generate LOG
* messages, but no error, for bogus combinations.
*/
for (addr = addrs; addr; addr = addr->ai_next)
{
#ifdef HAVE_UNIX_SOCKETS
/* Ignore AF_UNIX sockets, if any are returned. */
if (addr->ai_family == AF_UNIX)
continue;
#endif
2004-08-29 07:07:03 +02:00
if (++tries > 1)
ereport(LOG,
(errmsg("trying another address for the statistics collector")));
2006-10-04 02:30:14 +02:00
/*
* Create the socket.
*/
if ((pgStatSock = socket(addr->ai_family, SOCK_DGRAM, 0)) == PGINVALID_SOCKET)
{
ereport(LOG,
(errcode_for_socket_access(),
errmsg("could not create socket for statistics collector: %m")));
continue;
}
/*
2005-10-15 04:49:52 +02:00
* Bind it to a kernel assigned port on localhost and get the assigned
* port via getsockname().
*/
if (bind(pgStatSock, addr->ai_addr, addr->ai_addrlen) < 0)
{
ereport(LOG,
(errcode_for_socket_access(),
errmsg("could not bind socket for statistics collector: %m")));
closesocket(pgStatSock);
pgStatSock = PGINVALID_SOCKET;
continue;
}
alen = sizeof(pgStatAddr);
2017-06-21 20:39:04 +02:00
if (getsockname(pgStatSock, (struct sockaddr *) &pgStatAddr, &alen) < 0)
{
ereport(LOG,
(errcode_for_socket_access(),
errmsg("could not get address of socket for statistics collector: %m")));
closesocket(pgStatSock);
pgStatSock = PGINVALID_SOCKET;
continue;
}
/*
2005-10-15 04:49:52 +02:00
* Connect the socket to its own address. This saves a few cycles by
* not having to respecify the target address on every send. This also
* provides a kernel-level check that only packets from this same
* address will be received.
*/
2017-06-21 20:39:04 +02:00
if (connect(pgStatSock, (struct sockaddr *) &pgStatAddr, alen) < 0)
{
ereport(LOG,
(errcode_for_socket_access(),
errmsg("could not connect socket for statistics collector: %m")));
closesocket(pgStatSock);
pgStatSock = PGINVALID_SOCKET;
continue;
}
/*
2005-10-15 04:49:52 +02:00
* Try to send and receive a one-byte test message on the socket. This
* is to catch situations where the socket can be created but will not
* actually pass data (for instance, because kernel packet filtering
* rules prevent it).
*/
test_byte = TESTBYTEVAL;
retry1:
if (send(pgStatSock, &test_byte, 1, 0) != 1)
{
if (errno == EINTR)
goto retry1; /* if interrupted, just retry */
ereport(LOG,
(errcode_for_socket_access(),
errmsg("could not send test message on socket for statistics collector: %m")));
closesocket(pgStatSock);
pgStatSock = PGINVALID_SOCKET;
continue;
}
/*
2005-10-15 04:49:52 +02:00
* There could possibly be a little delay before the message can be
* received. We arbitrarily allow up to half a second before deciding
* it's broken.
*/
for (;;) /* need a loop to handle EINTR */
{
FD_ZERO(&rset);
2010-07-06 21:19:02 +02:00
FD_SET(pgStatSock, &rset);
tv.tv_sec = 0;
tv.tv_usec = 500000;
2004-08-29 07:07:03 +02:00
sel_res = select(pgStatSock + 1, &rset, NULL, NULL, &tv);
if (sel_res >= 0 || errno != EINTR)
break;
}
if (sel_res < 0)
{
ereport(LOG,
(errcode_for_socket_access(),
2005-10-15 04:49:52 +02:00
errmsg("select() failed in statistics collector: %m")));
closesocket(pgStatSock);
pgStatSock = PGINVALID_SOCKET;
continue;
}
if (sel_res == 0 || !FD_ISSET(pgStatSock, &rset))
{
/*
2005-10-15 04:49:52 +02:00
* This is the case we actually think is likely, so take pains to
* give a specific message for it.
*
* errno will not be set meaningfully here, so don't use it.
*/
ereport(LOG,
(errcode(ERRCODE_CONNECTION_FAILURE),
errmsg("test message did not get through on socket for statistics collector")));
closesocket(pgStatSock);
pgStatSock = PGINVALID_SOCKET;
continue;
}
test_byte++; /* just make sure variable is changed */
retry2:
if (recv(pgStatSock, &test_byte, 1, 0) != 1)
{
if (errno == EINTR)
goto retry2; /* if interrupted, just retry */
ereport(LOG,
(errcode_for_socket_access(),
errmsg("could not receive test message on socket for statistics collector: %m")));
closesocket(pgStatSock);
pgStatSock = PGINVALID_SOCKET;
continue;
}
2004-08-29 07:07:03 +02:00
if (test_byte != TESTBYTEVAL) /* strictly paranoia ... */
{
ereport(LOG,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("incorrect test message transmission on socket for statistics collector")));
closesocket(pgStatSock);
pgStatSock = PGINVALID_SOCKET;
continue;
}
/* If we get here, we have a working socket */
break;
}
/* Did we find a working address? */
if (!addr || pgStatSock == PGINVALID_SOCKET)
goto startup_failed;
/*
2005-10-15 04:49:52 +02:00
* Set the socket to non-blocking IO. This ensures that if the collector
* falls behind, statistics messages will be discarded; backends won't
* block waiting to send messages to the collector.
*/
if (!pg_set_noblock(pgStatSock))
{
ereport(LOG,
(errcode_for_socket_access(),
2004-08-29 07:07:03 +02:00
errmsg("could not set statistics collector socket to nonblocking mode: %m")));
goto startup_failed;
}
Try to ensure that stats collector's receive buffer size is at least 100KB. Since commit 4e37b3e15, buildfarm member frogmouth has been failing occasionally with symptoms indicating that some expected stats data is getting dropped. The reason that that commit changed the behavior seems probably to be that more data is getting shoved at the collector in a short span of time. In current sources, the stats test's first session sends about 9KB of data while exiting, which is probably the same as what was sent just before wait_for_stats() in the previous test design. But now, the test's second session is starting up concurrently, and it sends another 2KB (presumably reflecting its initial catalog accesses). Since frogmouth is running on Windows XP, which reputedly has a default socket receive buffer size of only 8KB, it is not very surprising if this has put us over the threshold where the receive buffer can overflow and drop messages. The same mechanism could very easily explain the intermittent stats test failures we've been seeing for years, since background processes such as the bgwriter will sometimes send data concurrently with all this, and could thus cause occasional buffer overflows. Hence, insert some code into pgstat_init() to increase the stats socket's receive buffer size to 100KB if it's less than that. (On failure, emit a LOG message, but keep going.) Modern systems seem to have default sizes in the range of 100KB-250KB, but older platforms don't. I couldn't find any platforms that wouldn't accept 100KB, so in theory this won't cause any portability problems. If this is successful at reducing the buildfarm failure rate in HEAD, we should back-patch it, because it's certain that similar buffer overflows happen in the field on platforms with small buffer sizes. Going forward, there might be an argument for trying to increase the buffer size even more, but let's take a baby step first. Discussion: https://postgr.es/m/22173.1494788088@sss.pgh.pa.us
2017-05-16 21:24:52 +02:00
/*
* Try to ensure that the socket's receive buffer is at least
* PGSTAT_MIN_RCVBUF bytes, so that it won't easily overflow and lose
* data. Use of UDP protocol means that we are willing to lose data under
* heavy load, but we don't want it to happen just because of ridiculously
* small default buffer sizes (such as 8KB on older Windows versions).
*/
{
int old_rcvbuf;
int new_rcvbuf;
ACCEPT_TYPE_ARG3 rcvbufsize = sizeof(old_rcvbuf);
if (getsockopt(pgStatSock, SOL_SOCKET, SO_RCVBUF,
(char *) &old_rcvbuf, &rcvbufsize) < 0)
{
elog(LOG, "getsockopt(SO_RCVBUF) failed: %m");
/* if we can't get existing size, always try to set it */
old_rcvbuf = 0;
}
new_rcvbuf = PGSTAT_MIN_RCVBUF;
if (old_rcvbuf < new_rcvbuf)
{
if (setsockopt(pgStatSock, SOL_SOCKET, SO_RCVBUF,
(char *) &new_rcvbuf, sizeof(new_rcvbuf)) < 0)
elog(LOG, "setsockopt(SO_RCVBUF) failed: %m");
}
}
pg_freeaddrinfo_all(hints.ai_family, addrs);
return;
startup_failed:
ereport(LOG,
(errmsg("disabling statistics collector for lack of working socket")));
if (addrs)
pg_freeaddrinfo_all(hints.ai_family, addrs);
if (pgStatSock != PGINVALID_SOCKET)
closesocket(pgStatSock);
pgStatSock = PGINVALID_SOCKET;
/*
* Adjust GUC variables to suppress useless activity, and for debugging
2007-11-15 22:14:46 +01:00
* purposes (seeing track_counts off is a clue that we failed here). We
* use PGC_S_OVERRIDE because there is no point in trying to turn it back
* on from postgresql.conf without a restart.
*/
SetConfigOption("track_counts", "off", PGC_INTERNAL, PGC_S_OVERRIDE);
}
/*
* subroutine for pgstat_reset_all
*/
static void
pgstat_reset_remove_files(const char *directory)
{
DIR *dir;
struct dirent *entry;
char fname[MAXPGPATH * 2];
dir = AllocateDir(directory);
while ((entry = ReadDir(dir, directory)) != NULL)
{
int nchars;
Oid tmp_oid;
/*
* Skip directory entries that don't match the file names we write.
* See get_dbstat_filename for the database-specific pattern.
*/
if (strncmp(entry->d_name, "global.", 7) == 0)
nchars = 7;
else
{
nchars = 0;
(void) sscanf(entry->d_name, "db_%u.%n",
&tmp_oid, &nchars);
if (nchars <= 0)
continue;
/* %u allows leading whitespace, so reject that */
if (strchr("0123456789", entry->d_name[3]) == NULL)
continue;
}
if (strcmp(entry->d_name + nchars, "tmp") != 0 &&
strcmp(entry->d_name + nchars, "stat") != 0)
continue;
snprintf(fname, sizeof(fname), "%s/%s", directory,
entry->d_name);
unlink(fname);
}
FreeDir(dir);
}
/*
* pgstat_reset_all() -
*
* Remove the stats files. This is currently used only if WAL
* recovery is needed after a crash.
*/
void
pgstat_reset_all(void)
{
pgstat_reset_remove_files(pgstat_stat_directory);
pgstat_reset_remove_files(PGSTAT_STAT_PERMANENT_DIRECTORY);
}
#ifdef EXEC_BACKEND
/*
* pgstat_forkexec() -
*
* Format up the arglist for, then fork and exec, statistics collector process
*/
static pid_t
pgstat_forkexec(void)
{
2004-08-29 07:07:03 +02:00
char *av[10];
int ac = 0;
av[ac++] = "postgres";
av[ac++] = "--forkcol";
av[ac++] = NULL; /* filled in by postmaster_forkexec */
av[ac] = NULL;
Assert(ac < lengthof(av));
return postmaster_forkexec(ac, av);
}
Phase 2 of pgindent updates. Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-06-21 21:18:54 +02:00
#endif /* EXEC_BACKEND */
/*
* pgstat_start() -
*
* Called from postmaster at startup or after an existing collector
* died. Attempt to fire up a fresh statistics collector.
*
* Returns PID of child process, or 0 if fail.
*
* Note: if fail, we will be called again from the postmaster main loop.
*/
int
pgstat_start(void)
{
time_t curtime;
pid_t pgStatPid;
/*
2007-11-15 22:14:46 +01:00
* Check that the socket is there, else pgstat_init failed and we can do
* nothing useful.
*/
if (pgStatSock == PGINVALID_SOCKET)
return 0;
/*
2005-10-15 04:49:52 +02:00
* Do nothing if too soon since last collector start. This is a safety
* valve to protect against continuous respawn attempts if the collector
* is dying immediately at launch. Note that since we will be re-called
2005-10-15 04:49:52 +02:00
* from the postmaster main loop, we will get another chance later.
*/
curtime = time(NULL);
if ((unsigned int) (curtime - last_pgstat_start_time) <
(unsigned int) PGSTAT_RESTART_INTERVAL)
return 0;
last_pgstat_start_time = curtime;
/*
* Okay, fork off the collector.
*/
#ifdef EXEC_BACKEND
switch ((pgStatPid = pgstat_forkexec()))
#else
switch ((pgStatPid = fork_process()))
#endif
{
case -1:
ereport(LOG,
(errmsg("could not fork statistics collector: %m")));
return 0;
#ifndef EXEC_BACKEND
case 0:
/* in postmaster child ... */
InitPostmasterChild();
/* Close the postmaster's sockets */
ClosePostmasterPorts(false);
/* Drop our connection to postmaster's shared memory, as well */
dsm_detach_all();
PGSharedMemoryDetach();
PgstatCollectorMain(0, NULL);
break;
#endif
default:
return (int) pgStatPid;
}
/* shouldn't get here */
return 0;
}
2007-11-15 22:14:46 +01:00
void
allow_immediate_pgstat_restart(void)
{
2007-11-15 22:14:46 +01:00
last_pgstat_start_time = 0;
}
/* ------------------------------------------------------------
* Public functions used by backends follow
*------------------------------------------------------------
*/
/* ----------
* pgstat_report_stat() -
*
* Must be called by processes that performs DML: tcop/postgres.c, logical
* receiver processes, SPI worker, etc. to send the so far collected
* per-table and function usage statistics to the collector. Note that this
* is called only when not within a transaction, so it is fair to use
* transaction stop time as an approximation of current time.
* ----------
*/
void
pgstat_report_stat(bool force)
{
/* we assume this inits to all zeroes: */
static const PgStat_TableCounts all_zeroes;
2007-11-15 22:14:46 +01:00
static TimestampTz last_report = 0;
TimestampTz now;
PgStat_MsgTabstat regular_msg;
PgStat_MsgTabstat shared_msg;
TabStatusArray *tsa;
int i;
/* Don't expend a clock check if nothing to do */
if ((pgStatTabList == NULL || pgStatTabList->tsa_used == 0) &&
pgStatXactCommit == 0 && pgStatXactRollback == 0 &&
!have_function_stats)
return;
/*
* Don't send a message unless it's been at least PGSTAT_STAT_INTERVAL
* msec since we last sent one, or the caller wants to force stats out.
*/
now = GetCurrentTransactionStopTimestamp();
if (!force &&
!TimestampDifferenceExceeds(last_report, now, PGSTAT_STAT_INTERVAL))
return;
last_report = now;
/*
* Destroy pgStatTabHash before we start invalidating PgStat_TableEntry
* entries it points to. (Should we fail partway through the loop below,
* it's okay to have removed the hashtable already --- the only
* consequence is we'd get multiple entries for the same table in the
* pgStatTabList, and that's safe.)
*/
if (pgStatTabHash)
hash_destroy(pgStatTabHash);
pgStatTabHash = NULL;
/*
* Scan through the TabStatusArray struct(s) to find tables that actually
* have counts, and build messages to send. We have to separate shared
2007-11-15 22:14:46 +01:00
* relations from regular ones because the databaseid field in the message
* header has to depend on that.
*/
regular_msg.m_databaseid = MyDatabaseId;
shared_msg.m_databaseid = InvalidOid;
regular_msg.m_nentries = 0;
shared_msg.m_nentries = 0;
for (tsa = pgStatTabList; tsa != NULL; tsa = tsa->tsa_next)
{
for (i = 0; i < tsa->tsa_used; i++)
{
PgStat_TableStatus *entry = &tsa->tsa_entries[i];
PgStat_MsgTabstat *this_msg;
PgStat_TableEntry *this_ent;
/* Shouldn't have any pending transaction-dependent counts */
Assert(entry->trans == NULL);
/*
2007-11-15 22:14:46 +01:00
* Ignore entries that didn't accumulate any actual counts, such
* as indexes that were opened by the planner but not used.
*/
if (memcmp(&entry->t_counts, &all_zeroes,
sizeof(PgStat_TableCounts)) == 0)
continue;
2007-11-15 22:14:46 +01:00
/*
* OK, insert data into the appropriate message, and send if full.
*/
this_msg = entry->t_shared ? &shared_msg : &regular_msg;
this_ent = &this_msg->m_entry[this_msg->m_nentries];
this_ent->t_id = entry->t_id;
memcpy(&this_ent->t_counts, &entry->t_counts,
sizeof(PgStat_TableCounts));
if (++this_msg->m_nentries >= PGSTAT_NUM_TABENTRIES)
{
pgstat_send_tabstat(this_msg);
this_msg->m_nentries = 0;
}
}
/* zero out TableStatus structs after use */
MemSet(tsa->tsa_entries, 0,
tsa->tsa_used * sizeof(PgStat_TableStatus));
tsa->tsa_used = 0;
}
/*
* Send partial messages. Make sure that any pending xact commit/abort
* gets counted, even if there are no table stats to send.
*/
if (regular_msg.m_nentries > 0 ||
pgStatXactCommit > 0 || pgStatXactRollback > 0)
pgstat_send_tabstat(&regular_msg);
if (shared_msg.m_nentries > 0)
pgstat_send_tabstat(&shared_msg);
/* Now, send function statistics */
pgstat_send_funcstats();
}
/*
* Subroutine for pgstat_report_stat: finish and send a tabstat message
*/
static void
pgstat_send_tabstat(PgStat_MsgTabstat *tsmsg)
{
int n;
int len;
/* It's unlikely we'd get here with no socket, but maybe not impossible */
if (pgStatSock == PGINVALID_SOCKET)
return;
/*
* Report and reset accumulated xact commit/rollback and I/O timings
* whenever we send a normal tabstat message
*/
if (OidIsValid(tsmsg->m_databaseid))
{
tsmsg->m_xact_commit = pgStatXactCommit;
tsmsg->m_xact_rollback = pgStatXactRollback;
tsmsg->m_block_read_time = pgStatBlockReadTime;
tsmsg->m_block_write_time = pgStatBlockWriteTime;
pgStatXactCommit = 0;
pgStatXactRollback = 0;
pgStatBlockReadTime = 0;
pgStatBlockWriteTime = 0;
}
else
{
tsmsg->m_xact_commit = 0;
tsmsg->m_xact_rollback = 0;
tsmsg->m_block_read_time = 0;
tsmsg->m_block_write_time = 0;
}
n = tsmsg->m_nentries;
len = offsetof(PgStat_MsgTabstat, m_entry[0]) +
n * sizeof(PgStat_TableEntry);
pgstat_setheader(&tsmsg->m_hdr, PGSTAT_MTYPE_TABSTAT);
pgstat_send(tsmsg, len);
}
/*
* Subroutine for pgstat_report_stat: populate and send a function stat message
*/
static void
pgstat_send_funcstats(void)
{
/* we assume this inits to all zeroes: */
static const PgStat_FunctionCounts all_zeroes;
PgStat_MsgFuncstat msg;
PgStat_BackendFunctionEntry *entry;
HASH_SEQ_STATUS fstat;
if (pgStatFunctions == NULL)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_FUNCSTAT);
msg.m_databaseid = MyDatabaseId;
msg.m_nentries = 0;
hash_seq_init(&fstat, pgStatFunctions);
while ((entry = (PgStat_BackendFunctionEntry *) hash_seq_search(&fstat)) != NULL)
{
PgStat_FunctionEntry *m_ent;
/* Skip it if no counts accumulated since last time */
if (memcmp(&entry->f_counts, &all_zeroes,
sizeof(PgStat_FunctionCounts)) == 0)
continue;
/* need to convert format of time accumulators */
m_ent = &msg.m_entry[msg.m_nentries];
m_ent->f_id = entry->f_id;
m_ent->f_numcalls = entry->f_counts.f_numcalls;
m_ent->f_total_time = INSTR_TIME_GET_MICROSEC(entry->f_counts.f_total_time);
m_ent->f_self_time = INSTR_TIME_GET_MICROSEC(entry->f_counts.f_self_time);
if (++msg.m_nentries >= PGSTAT_NUM_FUNCENTRIES)
{
pgstat_send(&msg, offsetof(PgStat_MsgFuncstat, m_entry[0]) +
msg.m_nentries * sizeof(PgStat_FunctionEntry));
msg.m_nentries = 0;
}
/* reset the entry's counts */
MemSet(&entry->f_counts, 0, sizeof(PgStat_FunctionCounts));
}
if (msg.m_nentries > 0)
pgstat_send(&msg, offsetof(PgStat_MsgFuncstat, m_entry[0]) +
msg.m_nentries * sizeof(PgStat_FunctionEntry));
have_function_stats = false;
}
/* ----------
* pgstat_vacuum_stat() -
*
* Will tell the collector about objects he can get rid of.
* ----------
*/
void
pgstat_vacuum_stat(void)
{
HTAB *htab;
PgStat_MsgTabpurge msg;
PgStat_MsgFuncpurge f_msg;
HASH_SEQ_STATUS hstat;
PgStat_StatDBEntry *dbentry;
PgStat_StatTabEntry *tabentry;
PgStat_StatFuncEntry *funcentry;
int len;
if (pgStatSock == PGINVALID_SOCKET)
return;
/*
2005-10-15 04:49:52 +02:00
* If not done for this transaction, read the statistics collector stats
* file into some hash tables.
*/
backend_read_statsfile();
/*
* Read pg_database and make a list of OIDs of all existing databases
*/
htab = pgstat_collect_oids(DatabaseRelationId);
/*
* Search the database hash table for dead databases and tell the
* collector to drop them.
*/
hash_seq_init(&hstat, pgStatDBHash);
while ((dbentry = (PgStat_StatDBEntry *) hash_seq_search(&hstat)) != NULL)
{
Oid dbid = dbentry->databaseid;
CHECK_FOR_INTERRUPTS();
/* the DB entry for shared tables (with InvalidOid) is never dropped */
if (OidIsValid(dbid) &&
hash_search(htab, (void *) &dbid, HASH_FIND, NULL) == NULL)
pgstat_drop_database(dbid);
}
/* Clean up */
hash_destroy(htab);
/*
* Lookup our own database entry; if not found, nothing more to do.
*/
dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
(void *) &MyDatabaseId,
HASH_FIND, NULL);
if (dbentry == NULL || dbentry->tables == NULL)
return;
/*
* Similarly to above, make a list of all known relations in this DB.
*/
htab = pgstat_collect_oids(RelationRelationId);
/*
* Initialize our messages table counter to zero
*/
msg.m_nentries = 0;
/*
* Check for all tables listed in stats hashtable if they still exist.
*/
hash_seq_init(&hstat, dbentry->tables);
while ((tabentry = (PgStat_StatTabEntry *) hash_seq_search(&hstat)) != NULL)
{
Oid tabid = tabentry->tableid;
CHECK_FOR_INTERRUPTS();
if (hash_search(htab, (void *) &tabid, HASH_FIND, NULL) != NULL)
continue;
/*
* Not there, so add this table's Oid to the message
*/
msg.m_tableid[msg.m_nentries++] = tabid;
/*
* If the message is full, send it out and reinitialize to empty
*/
if (msg.m_nentries >= PGSTAT_NUM_TABPURGE)
{
len = offsetof(PgStat_MsgTabpurge, m_tableid[0])
2017-06-21 20:39:04 +02:00
+ msg.m_nentries * sizeof(Oid);
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_TABPURGE);
msg.m_databaseid = MyDatabaseId;
pgstat_send(&msg, len);
msg.m_nentries = 0;
}
}
/*
* Send the rest
*/
if (msg.m_nentries > 0)
{
len = offsetof(PgStat_MsgTabpurge, m_tableid[0])
2017-06-21 20:39:04 +02:00
+ msg.m_nentries * sizeof(Oid);
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_TABPURGE);
msg.m_databaseid = MyDatabaseId;
pgstat_send(&msg, len);
}
/* Clean up */
hash_destroy(htab);
/*
* Now repeat the above steps for functions. However, we needn't bother
* in the common case where no function stats are being collected.
*/
if (dbentry->functions != NULL &&
hash_get_num_entries(dbentry->functions) > 0)
{
htab = pgstat_collect_oids(ProcedureRelationId);
pgstat_setheader(&f_msg.m_hdr, PGSTAT_MTYPE_FUNCPURGE);
f_msg.m_databaseid = MyDatabaseId;
f_msg.m_nentries = 0;
hash_seq_init(&hstat, dbentry->functions);
while ((funcentry = (PgStat_StatFuncEntry *) hash_seq_search(&hstat)) != NULL)
{
Oid funcid = funcentry->functionid;
CHECK_FOR_INTERRUPTS();
if (hash_search(htab, (void *) &funcid, HASH_FIND, NULL) != NULL)
continue;
/*
* Not there, so add this function's Oid to the message
*/
f_msg.m_functionid[f_msg.m_nentries++] = funcid;
/*
* If the message is full, send it out and reinitialize to empty
*/
if (f_msg.m_nentries >= PGSTAT_NUM_FUNCPURGE)
{
len = offsetof(PgStat_MsgFuncpurge, m_functionid[0])
2017-06-21 20:39:04 +02:00
+ f_msg.m_nentries * sizeof(Oid);
pgstat_send(&f_msg, len);
f_msg.m_nentries = 0;
}
}
/*
* Send the rest
*/
if (f_msg.m_nentries > 0)
{
len = offsetof(PgStat_MsgFuncpurge, m_functionid[0])
2017-06-21 20:39:04 +02:00
+ f_msg.m_nentries * sizeof(Oid);
pgstat_send(&f_msg, len);
}
hash_destroy(htab);
}
}
/* ----------
* pgstat_collect_oids() -
*
* Collect the OIDs of all objects listed in the specified system catalog
* into a temporary hash table. Caller should hash_destroy the result
* when done with it. (However, we make the table in CurrentMemoryContext
* so that it will be freed properly in event of an error.)
* ----------
*/
static HTAB *
pgstat_collect_oids(Oid catalogid)
{
HTAB *htab;
HASHCTL hash_ctl;
Relation rel;
HeapScanDesc scan;
HeapTuple tup;
Snapshot snapshot;
memset(&hash_ctl, 0, sizeof(hash_ctl));
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(Oid);
hash_ctl.hcxt = CurrentMemoryContext;
htab = hash_create("Temporary table of OIDs",
PGSTAT_TAB_HASH_SIZE,
&hash_ctl,
Improve hash_create's API for selecting simple-binary-key hash functions. Previously, if you wanted anything besides C-string hash keys, you had to specify a custom hashing function to hash_create(). Nearly all such callers were specifying tag_hash or oid_hash; which is tedious, and rather error-prone, since a caller could easily miss the opportunity to optimize by using hash_uint32 when appropriate. Replace this with a design whereby callers using simple binary-data keys just specify HASH_BLOBS and don't need to mess with specific support functions. hash_create() itself will take care of optimizing when the key size is four bytes. This nets out saving a few hundred bytes of code space, and offers a measurable performance improvement in tidbitmap.c (which was not exploiting the opportunity to use hash_uint32 for its 4-byte keys). There might be some wins elsewhere too, I didn't analyze closely. In future we could look into offering a similar optimized hashing function for 8-byte keys. Under this design that could be done in a centralized and machine-independent fashion, whereas getting it right for keys of platform-dependent sizes would've been notationally painful before. For the moment, the old way still works fine, so as not to break source code compatibility for loadable modules. Eventually we might want to remove tag_hash and friends from the exported API altogether, since there's no real need for them to be explicitly referenced from outside dynahash.c. Teodor Sigaev and Tom Lane
2014-12-18 19:36:29 +01:00
HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
rel = heap_open(catalogid, AccessShareLock);
snapshot = RegisterSnapshot(GetLatestSnapshot());
scan = heap_beginscan(rel, snapshot, 0, NULL);
while ((tup = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
2007-11-15 22:14:46 +01:00
Oid thisoid = HeapTupleGetOid(tup);
CHECK_FOR_INTERRUPTS();
(void) hash_search(htab, (void *) &thisoid, HASH_ENTER, NULL);
}
heap_endscan(scan);
UnregisterSnapshot(snapshot);
heap_close(rel, AccessShareLock);
return htab;
}
/* ----------
* pgstat_drop_database() -
*
* Tell the collector that we just dropped a database.
* (If the message gets lost, we will still clean the dead DB eventually
* via future invocations of pgstat_vacuum_stat().)
* ----------
*/
void
pgstat_drop_database(Oid databaseid)
{
PgStat_MsgDropdb msg;
if (pgStatSock == PGINVALID_SOCKET)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_DROPDB);
msg.m_databaseid = databaseid;
pgstat_send(&msg, sizeof(msg));
}
/* ----------
* pgstat_drop_relation() -
*
* Tell the collector that we just dropped a relation.
* (If the message gets lost, we will still clean the dead entry eventually
* via future invocations of pgstat_vacuum_stat().)
*
* Currently not used for lack of any good place to call it; we rely
* entirely on pgstat_vacuum_stat() to clean out stats for dead rels.
* ----------
*/
#ifdef NOT_USED
void
pgstat_drop_relation(Oid relid)
{
PgStat_MsgTabpurge msg;
int len;
if (pgStatSock == PGINVALID_SOCKET)
return;
msg.m_tableid[0] = relid;
msg.m_nentries = 1;
2017-06-21 20:39:04 +02:00
len = offsetof(PgStat_MsgTabpurge, m_tableid[0]) + sizeof(Oid);
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_TABPURGE);
msg.m_databaseid = MyDatabaseId;
pgstat_send(&msg, len);
}
Phase 2 of pgindent updates. Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-06-21 21:18:54 +02:00
#endif /* NOT_USED */
/* ----------
* pgstat_reset_counters() -
*
* Tell the statistics collector to reset counters for our database.
*
* Permission checking for this function is managed through the normal
* GRANT system.
* ----------
*/
void
pgstat_reset_counters(void)
{
PgStat_MsgResetcounter msg;
if (pgStatSock == PGINVALID_SOCKET)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RESETCOUNTER);
msg.m_databaseid = MyDatabaseId;
pgstat_send(&msg, sizeof(msg));
}
/* ----------
* pgstat_reset_shared_counters() -
*
* Tell the statistics collector to reset cluster-wide shared counters.
*
* Permission checking for this function is managed through the normal
* GRANT system.
* ----------
*/
void
pgstat_reset_shared_counters(const char *target)
{
PgStat_MsgResetsharedcounter msg;
if (pgStatSock == PGINVALID_SOCKET)
return;
if (strcmp(target, "archiver") == 0)
msg.m_resettarget = RESET_ARCHIVER;
else if (strcmp(target, "bgwriter") == 0)
msg.m_resettarget = RESET_BGWRITER;
else
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unrecognized reset target: \"%s\"", target),
errhint("Target must be \"archiver\" or \"bgwriter\".")));
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RESETSHAREDCOUNTER);
pgstat_send(&msg, sizeof(msg));
}
/* ----------
* pgstat_reset_single_counter() -
*
* Tell the statistics collector to reset a single counter.
*
* Permission checking for this function is managed through the normal
* GRANT system.
* ----------
*/
2010-02-26 03:01:40 +01:00
void
pgstat_reset_single_counter(Oid objoid, PgStat_Single_Reset_Type type)
{
PgStat_MsgResetsinglecounter msg;
if (pgStatSock == PGINVALID_SOCKET)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RESETSINGLECOUNTER);
msg.m_databaseid = MyDatabaseId;
msg.m_resettype = type;
msg.m_objectid = objoid;
pgstat_send(&msg, sizeof(msg));
}
/* ----------
* pgstat_report_autovac() -
*
* Called from autovacuum.c to report startup of an autovacuum process.
* We are called before InitPostgres is done, so can't rely on MyDatabaseId;
* the db OID must be passed in, instead.
* ----------
*/
void
pgstat_report_autovac(Oid dboid)
{
PgStat_MsgAutovacStart msg;
if (pgStatSock == PGINVALID_SOCKET)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_AUTOVAC_START);
msg.m_databaseid = dboid;
msg.m_start_time = GetCurrentTimestamp();
pgstat_send(&msg, sizeof(msg));
}
/* ---------
* pgstat_report_vacuum() -
*
* Tell the collector about the table we just vacuumed.
* ---------
*/
void
pgstat_report_vacuum(Oid tableoid, bool shared,
PgStat_Counter livetuples, PgStat_Counter deadtuples)
{
PgStat_MsgVacuum msg;
if (pgStatSock == PGINVALID_SOCKET || !pgstat_track_counts)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_VACUUM);
msg.m_databaseid = shared ? InvalidOid : MyDatabaseId;
msg.m_tableoid = tableoid;
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
msg.m_autovacuum = IsAutoVacuumWorkerProcess();
msg.m_vacuumtime = GetCurrentTimestamp();
msg.m_live_tuples = livetuples;
msg.m_dead_tuples = deadtuples;
pgstat_send(&msg, sizeof(msg));
}
/* --------
* pgstat_report_analyze() -
*
* Tell the collector about the table we just analyzed.
*
* Caller must provide new live- and dead-tuples estimates, as well as a
* flag indicating whether to reset the changes_since_analyze counter.
* --------
*/
void
Fix VACUUM so that it always updates pg_class.reltuples/relpages. When we added the ability for vacuum to skip heap pages by consulting the visibility map, we made it just not update the reltuples/relpages statistics if it skipped any pages. But this could leave us with extremely out-of-date stats for a table that contains any unchanging areas, especially for TOAST tables which never get processed by ANALYZE. In particular this could result in autovacuum making poor decisions about when to process the table, as in recent report from Florian Helmberger. And in general it's a bad idea to not update the stats at all. Instead, use the previous values of reltuples/relpages as an estimate of the tuple density in unvisited pages. This approach results in a "moving average" estimate of reltuples, which should converge to the correct value over multiple VACUUM and ANALYZE cycles even when individual measurements aren't very good. This new method for updating reltuples is used by both VACUUM and ANALYZE, with the result that we no longer need the grotty interconnections that caused ANALYZE to not update the stats depending on what had happened in the parent VACUUM command. Also, fix the logic for skipping all-visible pages during VACUUM so that it looks ahead rather than behind to decide what to do, as per a suggestion from Greg Stark. This eliminates useless scanning of all-visible pages at the start of the relation or just after a not-all-visible page. In particular, the first few pages of the relation will not be invariably included in the scanned pages, which seems to help in not overweighting them in the reltuples estimate. Back-patch to 8.4, where the visibility map was introduced.
2011-05-30 23:05:26 +02:00
pgstat_report_analyze(Relation rel,
PgStat_Counter livetuples, PgStat_Counter deadtuples,
bool resetcounter)
{
PgStat_MsgAnalyze msg;
if (pgStatSock == PGINVALID_SOCKET || !pgstat_track_counts)
return;
/*
* Unlike VACUUM, ANALYZE might be running inside a transaction that has
* already inserted and/or deleted rows in the target table. ANALYZE will
* have counted such rows as live or dead respectively. Because we will
* report our counts of such rows at transaction end, we should subtract
* off these counts from what we send to the collector now, else they'll
* be double-counted after commit. (This approach also ensures that the
* collector ends up with the right numbers if we abort instead of
* committing.)
*/
if (rel->pgstat_info != NULL)
{
PgStat_TableXactStatus *trans;
for (trans = rel->pgstat_info->trans; trans; trans = trans->upper)
{
livetuples -= trans->tuples_inserted - trans->tuples_deleted;
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
deadtuples -= trans->tuples_updated + trans->tuples_deleted;
}
/* count stuff inserted by already-aborted subxacts, too */
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
deadtuples -= rel->pgstat_info->t_counts.t_delta_dead_tuples;
/* Since ANALYZE's counts are estimates, we could have underflowed */
livetuples = Max(livetuples, 0);
deadtuples = Max(deadtuples, 0);
}
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_ANALYZE);
msg.m_databaseid = rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId;
msg.m_tableoid = RelationGetRelid(rel);
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
msg.m_autovacuum = IsAutoVacuumWorkerProcess();
msg.m_resetcounter = resetcounter;
msg.m_analyzetime = GetCurrentTimestamp();
msg.m_live_tuples = livetuples;
msg.m_dead_tuples = deadtuples;
pgstat_send(&msg, sizeof(msg));
}
/* --------
* pgstat_report_recovery_conflict() -
*
2011-04-10 17:42:00 +02:00
* Tell the collector about a Hot Standby recovery conflict.
* --------
*/
void
pgstat_report_recovery_conflict(int reason)
{
PgStat_MsgRecoveryConflict msg;
if (pgStatSock == PGINVALID_SOCKET || !pgstat_track_counts)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RECOVERYCONFLICT);
msg.m_databaseid = MyDatabaseId;
msg.m_reason = reason;
pgstat_send(&msg, sizeof(msg));
}
/* --------
* pgstat_report_deadlock() -
*
* Tell the collector about a deadlock detected.
* --------
*/
void
pgstat_report_deadlock(void)
{
PgStat_MsgDeadlock msg;
if (pgStatSock == PGINVALID_SOCKET || !pgstat_track_counts)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_DEADLOCK);
msg.m_databaseid = MyDatabaseId;
pgstat_send(&msg, sizeof(msg));
}
/* --------
* pgstat_report_tempfile() -
*
* Tell the collector about a temporary file.
* --------
*/
void
pgstat_report_tempfile(size_t filesize)
{
PgStat_MsgTempFile msg;
if (pgStatSock == PGINVALID_SOCKET || !pgstat_track_counts)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_TEMPFILE);
msg.m_databaseid = MyDatabaseId;
msg.m_filesize = filesize;
pgstat_send(&msg, sizeof(msg));
}
/* ----------
* pgstat_ping() -
*
* Send some junk data to the collector to increase traffic.
* ----------
*/
void
pgstat_ping(void)
{
PgStat_MsgDummy msg;
if (pgStatSock == PGINVALID_SOCKET)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_DUMMY);
pgstat_send(&msg, sizeof(msg));
}
/* ----------
* pgstat_send_inquiry() -
*
* Notify collector that we need fresh data.
* ----------
*/
static void
pgstat_send_inquiry(TimestampTz clock_time, TimestampTz cutoff_time, Oid databaseid)
{
PgStat_MsgInquiry msg;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_INQUIRY);
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
msg.clock_time = clock_time;
msg.cutoff_time = cutoff_time;
msg.databaseid = databaseid;
pgstat_send(&msg, sizeof(msg));
}
/*
* Initialize function call usage data.
* Called by the executor before invoking a function.
*/
void
pgstat_init_function_usage(FunctionCallInfoData *fcinfo,
PgStat_FunctionCallUsage *fcu)
{
PgStat_BackendFunctionEntry *htabent;
bool found;
if (pgstat_track_functions <= fcinfo->flinfo->fn_stats)
{
/* stats not wanted */
fcu->fs = NULL;
return;
}
if (!pgStatFunctions)
{
/* First time through - initialize function stat table */
HASHCTL hash_ctl;
memset(&hash_ctl, 0, sizeof(hash_ctl));
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(PgStat_BackendFunctionEntry);
pgStatFunctions = hash_create("Function stat entries",
PGSTAT_FUNCTION_HASH_SIZE,
&hash_ctl,
Improve hash_create's API for selecting simple-binary-key hash functions. Previously, if you wanted anything besides C-string hash keys, you had to specify a custom hashing function to hash_create(). Nearly all such callers were specifying tag_hash or oid_hash; which is tedious, and rather error-prone, since a caller could easily miss the opportunity to optimize by using hash_uint32 when appropriate. Replace this with a design whereby callers using simple binary-data keys just specify HASH_BLOBS and don't need to mess with specific support functions. hash_create() itself will take care of optimizing when the key size is four bytes. This nets out saving a few hundred bytes of code space, and offers a measurable performance improvement in tidbitmap.c (which was not exploiting the opportunity to use hash_uint32 for its 4-byte keys). There might be some wins elsewhere too, I didn't analyze closely. In future we could look into offering a similar optimized hashing function for 8-byte keys. Under this design that could be done in a centralized and machine-independent fashion, whereas getting it right for keys of platform-dependent sizes would've been notationally painful before. For the moment, the old way still works fine, so as not to break source code compatibility for loadable modules. Eventually we might want to remove tag_hash and friends from the exported API altogether, since there's no real need for them to be explicitly referenced from outside dynahash.c. Teodor Sigaev and Tom Lane
2014-12-18 19:36:29 +01:00
HASH_ELEM | HASH_BLOBS);
}
/* Get the stats entry for this function, create if necessary */
htabent = hash_search(pgStatFunctions, &fcinfo->flinfo->fn_oid,
HASH_ENTER, &found);
if (!found)
MemSet(&htabent->f_counts, 0, sizeof(PgStat_FunctionCounts));
fcu->fs = &htabent->f_counts;
/* save stats for this function, later used to compensate for recursion */
fcu->save_f_total_time = htabent->f_counts.f_total_time;
/* save current backend-wide total time */
fcu->save_total = total_func_time;
/* get clock time as of function start */
INSTR_TIME_SET_CURRENT(fcu->f_start);
}
/*
* find_funcstat_entry - find any existing PgStat_BackendFunctionEntry entry
* for specified function
*
* If no entry, return NULL, don't create a new one
*/
PgStat_BackendFunctionEntry *
find_funcstat_entry(Oid func_id)
{
if (pgStatFunctions == NULL)
return NULL;
return (PgStat_BackendFunctionEntry *) hash_search(pgStatFunctions,
(void *) &func_id,
HASH_FIND, NULL);
}
/*
* Calculate function call usage and update stat counters.
* Called by the executor after invoking a function.
*
* In the case of a set-returning function that runs in value-per-call mode,
* we will see multiple pgstat_init_function_usage/pgstat_end_function_usage
* calls for what the user considers a single call of the function. The
* finalize flag should be TRUE on the last call.
*/
void
pgstat_end_function_usage(PgStat_FunctionCallUsage *fcu, bool finalize)
{
PgStat_FunctionCounts *fs = fcu->fs;
instr_time f_total;
instr_time f_others;
instr_time f_self;
/* stats not wanted? */
if (fs == NULL)
return;
/* total elapsed time in this function call */
INSTR_TIME_SET_CURRENT(f_total);
INSTR_TIME_SUBTRACT(f_total, fcu->f_start);
/* self usage: elapsed minus anything already charged to other calls */
f_others = total_func_time;
INSTR_TIME_SUBTRACT(f_others, fcu->save_total);
f_self = f_total;
INSTR_TIME_SUBTRACT(f_self, f_others);
/* update backend-wide total time */
INSTR_TIME_ADD(total_func_time, f_self);
/*
* Compute the new f_total_time as the total elapsed time added to the
* pre-call value of f_total_time. This is necessary to avoid
* double-counting any time taken by recursive calls of myself. (We do
* not need any similar kluge for self time, since that already excludes
* any recursive calls.)
*/
INSTR_TIME_ADD(f_total, fcu->save_f_total_time);
/* update counters in function stats table */
if (finalize)
fs->f_numcalls++;
fs->f_total_time = f_total;
INSTR_TIME_ADD(fs->f_self_time, f_self);
/* indicate that we have something to send */
have_function_stats = true;
}
/* ----------
* pgstat_initstats() -
*
* Initialize a relcache entry to count access statistics.
* Called whenever a relation is opened.
*
* We assume that a relcache entry's pgstat_info field is zeroed by
* relcache.c when the relcache entry is made; thereafter it is long-lived
* data. We can avoid repeated searches of the TabStatus arrays when the
* same relation is touched repeatedly within a transaction.
* ----------
*/
void
pgstat_initstats(Relation rel)
{
Oid rel_id = rel->rd_id;
char relkind = rel->rd_rel->relkind;
/* We only count stats for things that have storage */
if (!(relkind == RELKIND_RELATION ||
relkind == RELKIND_MATVIEW ||
relkind == RELKIND_INDEX ||
relkind == RELKIND_TOASTVALUE ||
relkind == RELKIND_SEQUENCE))
{
rel->pgstat_info = NULL;
return;
}
if (pgStatSock == PGINVALID_SOCKET || !pgstat_track_counts)
{
/* We're not counting at all */
rel->pgstat_info = NULL;
return;
}
/*
2007-11-15 22:14:46 +01:00
* If we already set up this relation in the current transaction, nothing
* to do.
*/
if (rel->pgstat_info != NULL &&
rel->pgstat_info->t_id == rel_id)
return;
/* Else find or make the PgStat_TableStatus entry, and update link */
rel->pgstat_info = get_tabstat_entry(rel_id, rel->rd_rel->relisshared);
}
/*
* get_tabstat_entry - find or create a PgStat_TableStatus entry for rel
*/
static PgStat_TableStatus *
get_tabstat_entry(Oid rel_id, bool isshared)
{
TabStatHashEntry *hash_entry;
PgStat_TableStatus *entry;
TabStatusArray *tsa;
bool found;
/*
* Create hash table if we don't have it already.
*/
if (pgStatTabHash == NULL)
{
HASHCTL ctl;
memset(&ctl, 0, sizeof(ctl));
ctl.keysize = sizeof(Oid);
ctl.entrysize = sizeof(TabStatHashEntry);
pgStatTabHash = hash_create("pgstat TabStatusArray lookup hash table",
TABSTAT_QUANTUM,
&ctl,
HASH_ELEM | HASH_BLOBS);
}
/*
* Find an entry or create a new one.
*/
hash_entry = hash_search(pgStatTabHash, &rel_id, HASH_ENTER, &found);
if (!found)
{
/* initialize new entry with null pointer */
hash_entry->tsa_entry = NULL;
}
/*
* If entry is already valid, we're done.
*/
if (hash_entry->tsa_entry)
return hash_entry->tsa_entry;
/*
* Locate the first pgStatTabList entry with free space, making a new list
* entry if needed. Note that we could get an OOM failure here, but if so
* we have left the hashtable and the list in a consistent state.
*/
if (pgStatTabList == NULL)
{
/* Set up first pgStatTabList entry */
pgStatTabList = (TabStatusArray *)
MemoryContextAllocZero(TopMemoryContext,
sizeof(TabStatusArray));
}
tsa = pgStatTabList;
while (tsa->tsa_used >= TABSTAT_QUANTUM)
{
if (tsa->tsa_next == NULL)
tsa->tsa_next = (TabStatusArray *)
MemoryContextAllocZero(TopMemoryContext,
sizeof(TabStatusArray));
tsa = tsa->tsa_next;
}
/*
* Allocate a PgStat_TableStatus entry within this list entry. We assume
* the entry was already zeroed, either at creation or after last use.
*/
entry = &tsa->tsa_entries[tsa->tsa_used++];
entry->t_id = rel_id;
entry->t_shared = isshared;
/*
* Now we can fill the entry in pgStatTabHash.
*/
hash_entry->tsa_entry = entry;
return entry;
}
/*
* find_tabstat_entry - find any existing PgStat_TableStatus entry for rel
*
* If no entry, return NULL, don't create a new one
*
* Note: if we got an error in the most recent execution of pgstat_report_stat,
* it's possible that an entry exists but there's no hashtable entry for it.
* That's okay, we'll treat this case as "doesn't exist".
*/
PgStat_TableStatus *
find_tabstat_entry(Oid rel_id)
{
TabStatHashEntry *hash_entry;
/* If hashtable doesn't exist, there are no entries at all */
if (!pgStatTabHash)
return NULL;
hash_entry = hash_search(pgStatTabHash, &rel_id, HASH_FIND, NULL);
if (!hash_entry)
return NULL;
/* Note that this step could also return NULL, but that's correct */
return hash_entry->tsa_entry;
}
/*
* get_tabstat_stack_level - add a new (sub)transaction stack entry if needed
*/
static PgStat_SubXactStatus *
get_tabstat_stack_level(int nest_level)
{
PgStat_SubXactStatus *xact_state;
xact_state = pgStatXactStack;
if (xact_state == NULL || xact_state->nest_level != nest_level)
{
xact_state = (PgStat_SubXactStatus *)
MemoryContextAlloc(TopTransactionContext,
sizeof(PgStat_SubXactStatus));
xact_state->nest_level = nest_level;
xact_state->prev = pgStatXactStack;
xact_state->first = NULL;
pgStatXactStack = xact_state;
}
return xact_state;
}
/*
* add_tabstat_xact_level - add a new (sub)transaction state record
*/
static void
add_tabstat_xact_level(PgStat_TableStatus *pgstat_info, int nest_level)
{
PgStat_SubXactStatus *xact_state;
PgStat_TableXactStatus *trans;
/*
2007-11-15 22:14:46 +01:00
* If this is the first rel to be modified at the current nest level, we
* first have to push a transaction stack entry.
*/
xact_state = get_tabstat_stack_level(nest_level);
/* Now make a per-table stack entry */
trans = (PgStat_TableXactStatus *)
MemoryContextAllocZero(TopTransactionContext,
sizeof(PgStat_TableXactStatus));
trans->nest_level = nest_level;
trans->upper = pgstat_info->trans;
trans->parent = pgstat_info;
trans->next = xact_state->first;
xact_state->first = trans;
pgstat_info->trans = trans;
}
/*
* pgstat_count_heap_insert - count a tuple insertion of n tuples
*/
void
pgstat_count_heap_insert(Relation rel, PgStat_Counter n)
{
PgStat_TableStatus *pgstat_info = rel->pgstat_info;
if (pgstat_info != NULL)
{
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* We have to log the effect at the proper transactional level */
2007-11-15 22:14:46 +01:00
int nest_level = GetCurrentTransactionNestLevel();
if (pgstat_info->trans == NULL ||
pgstat_info->trans->nest_level != nest_level)
add_tabstat_xact_level(pgstat_info, nest_level);
pgstat_info->trans->tuples_inserted += n;
}
}
/*
* pgstat_count_heap_update - count a tuple update
*/
void
pgstat_count_heap_update(Relation rel, bool hot)
{
PgStat_TableStatus *pgstat_info = rel->pgstat_info;
if (pgstat_info != NULL)
{
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* We have to log the effect at the proper transactional level */
2007-11-15 22:14:46 +01:00
int nest_level = GetCurrentTransactionNestLevel();
if (pgstat_info->trans == NULL ||
pgstat_info->trans->nest_level != nest_level)
add_tabstat_xact_level(pgstat_info, nest_level);
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
pgstat_info->trans->tuples_updated++;
/* t_tuples_hot_updated is nontransactional, so just advance it */
if (hot)
pgstat_info->t_counts.t_tuples_hot_updated++;
}
}
/*
* pgstat_count_heap_delete - count a tuple deletion
*/
void
pgstat_count_heap_delete(Relation rel)
{
PgStat_TableStatus *pgstat_info = rel->pgstat_info;
if (pgstat_info != NULL)
{
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* We have to log the effect at the proper transactional level */
2007-11-15 22:14:46 +01:00
int nest_level = GetCurrentTransactionNestLevel();
if (pgstat_info->trans == NULL ||
pgstat_info->trans->nest_level != nest_level)
add_tabstat_xact_level(pgstat_info, nest_level);
pgstat_info->trans->tuples_deleted++;
}
}
/*
* pgstat_truncate_save_counters
*
* Whenever a table is truncated, we save its i/u/d counters so that they can
* be cleared, and if the (sub)xact that executed the truncate later aborts,
* the counters can be restored to the saved (pre-truncate) values. Note we do
* this on the first truncate in any particular subxact level only.
*/
static void
pgstat_truncate_save_counters(PgStat_TableXactStatus *trans)
{
if (!trans->truncated)
{
trans->inserted_pre_trunc = trans->tuples_inserted;
trans->updated_pre_trunc = trans->tuples_updated;
trans->deleted_pre_trunc = trans->tuples_deleted;
trans->truncated = true;
}
}
/*
* pgstat_truncate_restore_counters - restore counters when a truncate aborts
*/
static void
pgstat_truncate_restore_counters(PgStat_TableXactStatus *trans)
{
if (trans->truncated)
{
trans->tuples_inserted = trans->inserted_pre_trunc;
trans->tuples_updated = trans->updated_pre_trunc;
trans->tuples_deleted = trans->deleted_pre_trunc;
}
}
/*
* pgstat_count_truncate - update tuple counters due to truncate
*/
void
pgstat_count_truncate(Relation rel)
{
PgStat_TableStatus *pgstat_info = rel->pgstat_info;
if (pgstat_info != NULL)
{
/* We have to log the effect at the proper transactional level */
int nest_level = GetCurrentTransactionNestLevel();
if (pgstat_info->trans == NULL ||
pgstat_info->trans->nest_level != nest_level)
add_tabstat_xact_level(pgstat_info, nest_level);
pgstat_truncate_save_counters(pgstat_info->trans);
pgstat_info->trans->tuples_inserted = 0;
pgstat_info->trans->tuples_updated = 0;
pgstat_info->trans->tuples_deleted = 0;
}
}
/*
* pgstat_update_heap_dead_tuples - update dead-tuples count
*
* The semantics of this are that we are reporting the nontransactional
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
* recovery of "delta" dead tuples; so t_delta_dead_tuples decreases
* rather than increasing, and the change goes straight into the per-table
* counter, not into transactional state.
*/
void
pgstat_update_heap_dead_tuples(Relation rel, int delta)
{
PgStat_TableStatus *pgstat_info = rel->pgstat_info;
if (pgstat_info != NULL)
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
pgstat_info->t_counts.t_delta_dead_tuples -= delta;
}
/* ----------
* AtEOXact_PgStat
*
* Called from access/transam/xact.c at top-level transaction commit/abort.
* ----------
*/
void
AtEOXact_PgStat(bool isCommit)
{
PgStat_SubXactStatus *xact_state;
/*
* Count transaction commit or abort. (We use counters, not just bools,
* in case the reporting message isn't sent right away.)
*/
if (isCommit)
pgStatXactCommit++;
else
pgStatXactRollback++;
/*
* Transfer transactional insert/update counts into the base tabstat
2007-11-15 22:14:46 +01:00
* entries. We don't bother to free any of the transactional state, since
* it's all in TopTransactionContext and will go away anyway.
*/
xact_state = pgStatXactStack;
if (xact_state != NULL)
{
PgStat_TableXactStatus *trans;
Assert(xact_state->nest_level == 1);
Assert(xact_state->prev == NULL);
for (trans = xact_state->first; trans != NULL; trans = trans->next)
{
PgStat_TableStatus *tabstat;
Assert(trans->nest_level == 1);
Assert(trans->upper == NULL);
tabstat = trans->parent;
Assert(tabstat->trans == trans);
/* restore pre-truncate stats (if any) in case of aborted xact */
if (!isCommit)
pgstat_truncate_restore_counters(trans);
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* count attempted actions regardless of commit/abort */
tabstat->t_counts.t_tuples_inserted += trans->tuples_inserted;
tabstat->t_counts.t_tuples_updated += trans->tuples_updated;
tabstat->t_counts.t_tuples_deleted += trans->tuples_deleted;
if (isCommit)
{
tabstat->t_counts.t_truncated = trans->truncated;
if (trans->truncated)
{
/* forget live/dead stats seen by backend thus far */
tabstat->t_counts.t_delta_live_tuples = 0;
tabstat->t_counts.t_delta_dead_tuples = 0;
}
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* insert adds a live tuple, delete removes one */
tabstat->t_counts.t_delta_live_tuples +=
trans->tuples_inserted - trans->tuples_deleted;
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* update and delete each create a dead tuple */
tabstat->t_counts.t_delta_dead_tuples +=
trans->tuples_updated + trans->tuples_deleted;
/* insert, update, delete each count as one change event */
tabstat->t_counts.t_changed_tuples +=
trans->tuples_inserted + trans->tuples_updated +
trans->tuples_deleted;
}
else
{
/* inserted tuples are dead, deleted tuples are unaffected */
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
tabstat->t_counts.t_delta_dead_tuples +=
trans->tuples_inserted + trans->tuples_updated;
/* an aborted xact generates no changed_tuple events */
}
tabstat->trans = NULL;
}
}
pgStatXactStack = NULL;
/* Make sure any stats snapshot is thrown away */
pgstat_clear_snapshot();
}
/* ----------
* AtEOSubXact_PgStat
*
* Called from access/transam/xact.c at subtransaction commit/abort.
* ----------
*/
void
AtEOSubXact_PgStat(bool isCommit, int nestDepth)
{
PgStat_SubXactStatus *xact_state;
/*
* Transfer transactional insert/update counts into the next higher
* subtransaction state.
*/
xact_state = pgStatXactStack;
if (xact_state != NULL &&
xact_state->nest_level >= nestDepth)
{
PgStat_TableXactStatus *trans;
PgStat_TableXactStatus *next_trans;
/* delink xact_state from stack immediately to simplify reuse case */
pgStatXactStack = xact_state->prev;
for (trans = xact_state->first; trans != NULL; trans = next_trans)
{
PgStat_TableStatus *tabstat;
next_trans = trans->next;
Assert(trans->nest_level == nestDepth);
tabstat = trans->parent;
Assert(tabstat->trans == trans);
if (isCommit)
{
if (trans->upper && trans->upper->nest_level == nestDepth - 1)
{
if (trans->truncated)
{
/* propagate the truncate status one level up */
pgstat_truncate_save_counters(trans->upper);
/* replace upper xact stats with ours */
trans->upper->tuples_inserted = trans->tuples_inserted;
trans->upper->tuples_updated = trans->tuples_updated;
trans->upper->tuples_deleted = trans->tuples_deleted;
}
else
{
trans->upper->tuples_inserted += trans->tuples_inserted;
trans->upper->tuples_updated += trans->tuples_updated;
trans->upper->tuples_deleted += trans->tuples_deleted;
}
tabstat->trans = trans->upper;
pfree(trans);
}
else
{
/*
2007-11-15 22:14:46 +01:00
* When there isn't an immediate parent state, we can just
* reuse the record instead of going through a
* palloc/pfree pushup (this works since it's all in
2007-11-15 22:14:46 +01:00
* TopTransactionContext anyway). We have to re-link it
* into the parent level, though, and that might mean
* pushing a new entry into the pgStatXactStack.
*/
PgStat_SubXactStatus *upper_xact_state;
upper_xact_state = get_tabstat_stack_level(nestDepth - 1);
trans->next = upper_xact_state->first;
upper_xact_state->first = trans;
trans->nest_level = nestDepth - 1;
}
}
else
{
/*
2010-02-26 03:01:40 +01:00
* On abort, update top-level tabstat counts, then forget the
* subtransaction
*/
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* first restore values obliterated by truncate */
pgstat_truncate_restore_counters(trans);
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* count attempted actions regardless of commit/abort */
tabstat->t_counts.t_tuples_inserted += trans->tuples_inserted;
tabstat->t_counts.t_tuples_updated += trans->tuples_updated;
tabstat->t_counts.t_tuples_deleted += trans->tuples_deleted;
/* inserted tuples are dead, deleted tuples are unaffected */
tabstat->t_counts.t_delta_dead_tuples +=
trans->tuples_inserted + trans->tuples_updated;
tabstat->trans = trans->upper;
pfree(trans);
}
}
pfree(xact_state);
}
}
/*
* AtPrepare_PgStat
* Save the transactional stats state at 2PC transaction prepare.
*
* In this phase we just generate 2PC records for all the pending
* transaction-dependent stats work.
*/
void
AtPrepare_PgStat(void)
{
PgStat_SubXactStatus *xact_state;
xact_state = pgStatXactStack;
if (xact_state != NULL)
{
PgStat_TableXactStatus *trans;
Assert(xact_state->nest_level == 1);
Assert(xact_state->prev == NULL);
for (trans = xact_state->first; trans != NULL; trans = trans->next)
{
PgStat_TableStatus *tabstat;
TwoPhasePgStatRecord record;
Assert(trans->nest_level == 1);
Assert(trans->upper == NULL);
tabstat = trans->parent;
Assert(tabstat->trans == trans);
record.tuples_inserted = trans->tuples_inserted;
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
record.tuples_updated = trans->tuples_updated;
record.tuples_deleted = trans->tuples_deleted;
record.inserted_pre_trunc = trans->inserted_pre_trunc;
record.updated_pre_trunc = trans->updated_pre_trunc;
record.deleted_pre_trunc = trans->deleted_pre_trunc;
record.t_id = tabstat->t_id;
record.t_shared = tabstat->t_shared;
record.t_truncated = trans->truncated;
RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0,
&record, sizeof(TwoPhasePgStatRecord));
}
}
}
/*
* PostPrepare_PgStat
* Clean up after successful PREPARE.
*
* All we need do here is unlink the transaction stats state from the
* nontransactional state. The nontransactional action counts will be
* reported to the stats collector immediately, while the effects on live
* and dead tuple counts are preserved in the 2PC state file.
*
* Note: AtEOXact_PgStat is not called during PREPARE.
*/
void
PostPrepare_PgStat(void)
{
PgStat_SubXactStatus *xact_state;
/*
2007-11-15 22:14:46 +01:00
* We don't bother to free any of the transactional state, since it's all
* in TopTransactionContext and will go away anyway.
*/
xact_state = pgStatXactStack;
if (xact_state != NULL)
{
PgStat_TableXactStatus *trans;
for (trans = xact_state->first; trans != NULL; trans = trans->next)
{
PgStat_TableStatus *tabstat;
tabstat = trans->parent;
tabstat->trans = NULL;
}
}
pgStatXactStack = NULL;
/* Make sure any stats snapshot is thrown away */
pgstat_clear_snapshot();
}
/*
* 2PC processing routine for COMMIT PREPARED case.
*
* Load the saved counts into our local pgstats state.
*/
void
pgstat_twophase_postcommit(TransactionId xid, uint16 info,
void *recdata, uint32 len)
{
TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata;
PgStat_TableStatus *pgstat_info;
/* Find or create a tabstat entry for the rel */
pgstat_info = get_tabstat_entry(rec->t_id, rec->t_shared);
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* Same math as in AtEOXact_PgStat, commit case */
pgstat_info->t_counts.t_tuples_inserted += rec->tuples_inserted;
pgstat_info->t_counts.t_tuples_updated += rec->tuples_updated;
pgstat_info->t_counts.t_tuples_deleted += rec->tuples_deleted;
pgstat_info->t_counts.t_truncated = rec->t_truncated;
if (rec->t_truncated)
{
/* forget live/dead stats seen by backend thus far */
pgstat_info->t_counts.t_delta_live_tuples = 0;
pgstat_info->t_counts.t_delta_dead_tuples = 0;
}
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
pgstat_info->t_counts.t_delta_live_tuples +=
rec->tuples_inserted - rec->tuples_deleted;
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
pgstat_info->t_counts.t_delta_dead_tuples +=
rec->tuples_updated + rec->tuples_deleted;
pgstat_info->t_counts.t_changed_tuples +=
rec->tuples_inserted + rec->tuples_updated +
rec->tuples_deleted;
}
/*
* 2PC processing routine for ROLLBACK PREPARED case.
*
* Load the saved counts into our local pgstats state, but treat them
* as aborted.
*/
void
pgstat_twophase_postabort(TransactionId xid, uint16 info,
void *recdata, uint32 len)
{
TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata;
PgStat_TableStatus *pgstat_info;
/* Find or create a tabstat entry for the rel */
pgstat_info = get_tabstat_entry(rec->t_id, rec->t_shared);
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* Same math as in AtEOXact_PgStat, abort case */
if (rec->t_truncated)
{
rec->tuples_inserted = rec->inserted_pre_trunc;
rec->tuples_updated = rec->updated_pre_trunc;
rec->tuples_deleted = rec->deleted_pre_trunc;
}
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
pgstat_info->t_counts.t_tuples_inserted += rec->tuples_inserted;
pgstat_info->t_counts.t_tuples_updated += rec->tuples_updated;
pgstat_info->t_counts.t_tuples_deleted += rec->tuples_deleted;
pgstat_info->t_counts.t_delta_dead_tuples +=
rec->tuples_inserted + rec->tuples_updated;
}
/* ----------
* pgstat_fetch_stat_dbentry() -
*
* Support function for the SQL-callable pgstat* functions. Returns
* the collected statistics for one database or NULL. NULL doesn't mean
* that the database doesn't exist, it is just not yet known by the
* collector, so the caller is better off to report ZERO instead.
* ----------
*/
PgStat_StatDBEntry *
pgstat_fetch_stat_dbentry(Oid dbid)
{
/*
2005-10-15 04:49:52 +02:00
* If not done for this transaction, read the statistics collector stats
* file into some hash tables.
*/
backend_read_statsfile();
/*
* Lookup the requested database; return NULL if not found
*/
return (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
(void *) &dbid,
HASH_FIND, NULL);
}
/* ----------
* pgstat_fetch_stat_tabentry() -
*
* Support function for the SQL-callable pgstat* functions. Returns
* the collected statistics for one table or NULL. NULL doesn't mean
* that the table doesn't exist, it is just not yet known by the
* collector, so the caller is better off to report ZERO instead.
* ----------
*/
PgStat_StatTabEntry *
pgstat_fetch_stat_tabentry(Oid relid)
{
Oid dbid;
PgStat_StatDBEntry *dbentry;
PgStat_StatTabEntry *tabentry;
/*
2005-10-15 04:49:52 +02:00
* If not done for this transaction, read the statistics collector stats
* file into some hash tables.
*/
backend_read_statsfile();
/*
* Lookup our database, then look in its table hash table.
*/
dbid = MyDatabaseId;
dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
(void *) &dbid,
HASH_FIND, NULL);
if (dbentry != NULL && dbentry->tables != NULL)
{
tabentry = (PgStat_StatTabEntry *) hash_search(dbentry->tables,
(void *) &relid,
HASH_FIND, NULL);
if (tabentry)
return tabentry;
}
/*
* If we didn't find it, maybe it's a shared table.
*/
dbid = InvalidOid;
dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
(void *) &dbid,
HASH_FIND, NULL);
if (dbentry != NULL && dbentry->tables != NULL)
{
tabentry = (PgStat_StatTabEntry *) hash_search(dbentry->tables,
(void *) &relid,
HASH_FIND, NULL);
if (tabentry)
return tabentry;
}
return NULL;
}
/* ----------
* pgstat_fetch_stat_funcentry() -
*
* Support function for the SQL-callable pgstat* functions. Returns
* the collected statistics for one function or NULL.
* ----------
*/
PgStat_StatFuncEntry *
pgstat_fetch_stat_funcentry(Oid func_id)
{
PgStat_StatDBEntry *dbentry;
PgStat_StatFuncEntry *funcentry = NULL;
/* load the stats file if needed */
backend_read_statsfile();
/* Lookup our database, then find the requested function. */
dbentry = pgstat_fetch_stat_dbentry(MyDatabaseId);
if (dbentry != NULL && dbentry->functions != NULL)
{
funcentry = (PgStat_StatFuncEntry *) hash_search(dbentry->functions,
(void *) &func_id,
HASH_FIND, NULL);
}
return funcentry;
}
/* ----------
* pgstat_fetch_stat_beentry() -
*
* Support function for the SQL-callable pgstat* functions. Returns
* our local copy of the current-activity entry for one backend.
*
* NB: caller is responsible for a check if the user is permitted to see
* this info (especially the querystring).
* ----------
*/
PgBackendStatus *
pgstat_fetch_stat_beentry(int beid)
{
pgstat_read_current_status();
if (beid < 1 || beid > localNumBackends)
return NULL;
return &localBackendStatusTable[beid - 1].backendStatus;
}
/* ----------
* pgstat_fetch_stat_local_beentry() -
*
2016-10-26 10:12:31 +02:00
* Like pgstat_fetch_stat_beentry() but with locally computed additions (like
* xid and xmin values of the backend)
*
* NB: caller is responsible for a check if the user is permitted to see
* this info (especially the querystring).
* ----------
*/
LocalPgBackendStatus *
pgstat_fetch_stat_local_beentry(int beid)
{
pgstat_read_current_status();
if (beid < 1 || beid > localNumBackends)
return NULL;
return &localBackendStatusTable[beid - 1];
}
/* ----------
* pgstat_fetch_stat_numbackends() -
*
* Support function for the SQL-callable pgstat* functions. Returns
* the maximum current backend id.
* ----------
*/
int
pgstat_fetch_stat_numbackends(void)
{
pgstat_read_current_status();
return localNumBackends;
}
/*
* ---------
* pgstat_fetch_stat_archiver() -
*
* Support function for the SQL-callable pgstat* functions. Returns
* a pointer to the archiver statistics struct.
* ---------
*/
PgStat_ArchiverStats *
pgstat_fetch_stat_archiver(void)
{
backend_read_statsfile();
return &archiverStats;
}
/*
* ---------
* pgstat_fetch_global() -
*
2007-11-15 22:14:46 +01:00
* Support function for the SQL-callable pgstat* functions. Returns
* a pointer to the global statistics struct.
* ---------
*/
PgStat_GlobalStats *
pgstat_fetch_global(void)
{
backend_read_statsfile();
return &globalStats;
}
/* ------------------------------------------------------------
* Functions for management of the shared-memory PgBackendStatus array
* ------------------------------------------------------------
*/
static PgBackendStatus *BackendStatusArray = NULL;
static PgBackendStatus *MyBEEntry = NULL;
static char *BackendAppnameBuffer = NULL;
static char *BackendClientHostnameBuffer = NULL;
static char *BackendActivityBuffer = NULL;
static Size BackendActivityBufferSize = 0;
#ifdef USE_SSL
static PgBackendSSLStatus *BackendSslStatusBuffer = NULL;
#endif
/*
* Report shared-memory space needed by CreateSharedBackendStatus.
*/
Size
BackendStatusShmemSize(void)
{
Size size;
/* BackendStatusArray: */
size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
/* BackendAppnameBuffer: */
size = add_size(size,
mul_size(NAMEDATALEN, NumBackendStatSlots));
/* BackendClientHostnameBuffer: */
size = add_size(size,
mul_size(NAMEDATALEN, NumBackendStatSlots));
/* BackendActivityBuffer: */
size = add_size(size,
mul_size(pgstat_track_activity_query_size, NumBackendStatSlots));
#ifdef USE_SSL
/* BackendSslStatusBuffer: */
size = add_size(size,
mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots));
#endif
return size;
}
/*
* Initialize the shared status array and several string buffers
* during postmaster startup.
*/
void
CreateSharedBackendStatus(void)
{
Size size;
bool found;
int i;
char *buffer;
/* Create or attach to the shared array */
size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
BackendStatusArray = (PgBackendStatus *)
ShmemInitStruct("Backend Status Array", size, &found);
if (!found)
{
/*
* We're the first - initialize.
*/
MemSet(BackendStatusArray, 0, size);
}
/* Create or attach to the shared appname buffer */
size = mul_size(NAMEDATALEN, NumBackendStatSlots);
BackendAppnameBuffer = (char *)
ShmemInitStruct("Backend Application Name Buffer", size, &found);
if (!found)
{
MemSet(BackendAppnameBuffer, 0, size);
/* Initialize st_appname pointers. */
buffer = BackendAppnameBuffer;
for (i = 0; i < NumBackendStatSlots; i++)
{
BackendStatusArray[i].st_appname = buffer;
buffer += NAMEDATALEN;
}
}
/* Create or attach to the shared client hostname buffer */
size = mul_size(NAMEDATALEN, NumBackendStatSlots);
BackendClientHostnameBuffer = (char *)
ShmemInitStruct("Backend Client Host Name Buffer", size, &found);
if (!found)
{
MemSet(BackendClientHostnameBuffer, 0, size);
/* Initialize st_clienthostname pointers. */
buffer = BackendClientHostnameBuffer;
for (i = 0; i < NumBackendStatSlots; i++)
{
BackendStatusArray[i].st_clienthostname = buffer;
buffer += NAMEDATALEN;
}
}
/* Create or attach to the shared activity buffer */
BackendActivityBufferSize = mul_size(pgstat_track_activity_query_size,
NumBackendStatSlots);
BackendActivityBuffer = (char *)
ShmemInitStruct("Backend Activity Buffer",
BackendActivityBufferSize,
&found);
if (!found)
{
MemSet(BackendActivityBuffer, 0, BackendActivityBufferSize);
/* Initialize st_activity pointers. */
buffer = BackendActivityBuffer;
for (i = 0; i < NumBackendStatSlots; i++)
{
BackendStatusArray[i].st_activity_raw = buffer;
buffer += pgstat_track_activity_query_size;
}
}
#ifdef USE_SSL
/* Create or attach to the shared SSL status buffer */
size = mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots);
BackendSslStatusBuffer = (PgBackendSSLStatus *)
ShmemInitStruct("Backend SSL Status Buffer", size, &found);
if (!found)
{
PgBackendSSLStatus *ptr;
MemSet(BackendSslStatusBuffer, 0, size);
/* Initialize st_sslstatus pointers. */
ptr = BackendSslStatusBuffer;
for (i = 0; i < NumBackendStatSlots; i++)
{
BackendStatusArray[i].st_sslstatus = ptr;
ptr++;
}
}
#endif
}
/* ----------
* pgstat_initialize() -
*
* Initialize pgstats state, and set up our on-proc-exit hook.
* Called from InitPostgres and AuxiliaryProcessMain. For auxiliary process,
* MyBackendId is invalid. Otherwise, MyBackendId must be set,
* but we must not have started any transaction yet (since the
* exit hook must run after the last transaction exit).
* NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
* ----------
*/
void
pgstat_initialize(void)
{
/* Initialize MyBEEntry */
if (MyBackendId != InvalidBackendId)
{
Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
MyBEEntry = &BackendStatusArray[MyBackendId - 1];
}
else
{
/* Must be an auxiliary process */
Assert(MyAuxProcType != NotAnAuxProcess);
/*
* Assign the MyBEEntry for an auxiliary process. Since it doesn't
* have a BackendId, the slot is statically allocated based on the
* auxiliary process type (MyAuxProcType). Backends use slots indexed
* in the range from 1 to MaxBackends (inclusive), so we use
* MaxBackends + AuxBackendType + 1 as the index of the slot for an
* auxiliary process.
*/
MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
}
/* Set up a process-exit hook to clean up */
on_shmem_exit(pgstat_beshutdown_hook, 0);
}
/* ----------
* pgstat_bestart() -
*
* Initialize this backend's entry in the PgBackendStatus array.
* Called from InitPostgres.
*
* Apart from auxiliary processes, MyBackendId, MyDatabaseId,
* session userid, and application_name must be set for a
* backend (hence, this cannot be combined with pgstat_initialize).
* ----------
*/
void
pgstat_bestart(void)
{
SockAddr clientaddr;
volatile PgBackendStatus *beentry;
/*
2007-11-15 22:14:46 +01:00
* To minimize the time spent modifying the PgBackendStatus entry, fetch
* all the needed data first.
*/
/*
* We may not have a MyProcPort (eg, if this is the autovacuum process).
* If so, use all-zeroes client address, which is dealt with specially in
* pg_stat_get_backend_client_addr and pg_stat_get_backend_client_port.
*/
if (MyProcPort)
memcpy(&clientaddr, &MyProcPort->raddr, sizeof(clientaddr));
else
MemSet(&clientaddr, 0, sizeof(clientaddr));
/*
* Initialize my status entry, following the protocol of bumping
2006-10-04 02:30:14 +02:00
* st_changecount before and after; and make sure it's even afterwards. We
* use a volatile pointer here to ensure the compiler doesn't try to get
* cute.
*/
beentry = MyBEEntry;
/* pgstats state must be initialized from pgstat_initialize() */
Assert(beentry != NULL);
if (MyBackendId != InvalidBackendId)
{
if (IsAutoVacuumLauncherProcess())
{
/* Autovacuum Launcher */
beentry->st_backendType = B_AUTOVAC_LAUNCHER;
}
else if (IsAutoVacuumWorkerProcess())
{
/* Autovacuum Worker */
beentry->st_backendType = B_AUTOVAC_WORKER;
}
else if (am_walsender)
{
/* Wal sender */
beentry->st_backendType = B_WAL_SENDER;
}
else if (IsBackgroundWorker)
{
/* bgworker */
beentry->st_backendType = B_BG_WORKER;
}
else
{
/* client-backend */
beentry->st_backendType = B_BACKEND;
}
}
else
{
/* Must be an auxiliary process */
Assert(MyAuxProcType != NotAnAuxProcess);
switch (MyAuxProcType)
{
case StartupProcess:
beentry->st_backendType = B_STARTUP;
break;
case BgWriterProcess:
beentry->st_backendType = B_BG_WRITER;
break;
case CheckpointerProcess:
beentry->st_backendType = B_CHECKPOINTER;
break;
case WalWriterProcess:
beentry->st_backendType = B_WAL_WRITER;
break;
case WalReceiverProcess:
beentry->st_backendType = B_WAL_RECEIVER;
break;
default:
elog(FATAL, "unrecognized process type: %d",
(int) MyAuxProcType);
proc_exit(1);
}
}
2006-10-04 02:30:14 +02:00
do
{
pgstat_increment_changecount_before(beentry);
} while ((beentry->st_changecount & 1) == 0);
beentry->st_procpid = MyProcPid;
beentry->st_proc_start_timestamp = MyStartTimestamp;
beentry->st_activity_start_timestamp = 0;
beentry->st_state_start_timestamp = 0;
beentry->st_xact_start_timestamp = 0;
beentry->st_databaseid = MyDatabaseId;
/* We have userid for client-backends, wal-sender and bgworker processes */
if (beentry->st_backendType == B_BACKEND
|| beentry->st_backendType == B_WAL_SENDER
|| beentry->st_backendType == B_BG_WORKER)
beentry->st_userid = GetSessionUserId();
else
beentry->st_userid = InvalidOid;
beentry->st_clientaddr = clientaddr;
if (MyProcPort && MyProcPort->remote_hostname)
strlcpy(beentry->st_clienthostname, MyProcPort->remote_hostname,
NAMEDATALEN);
else
beentry->st_clienthostname[0] = '\0';
#ifdef USE_SSL
if (MyProcPort && MyProcPort->ssl != NULL)
{
beentry->st_ssl = true;
beentry->st_sslstatus->ssl_bits = be_tls_get_cipher_bits(MyProcPort);
beentry->st_sslstatus->ssl_compression = be_tls_get_compression(MyProcPort);
strlcpy(beentry->st_sslstatus->ssl_version, be_tls_get_version(MyProcPort), NAMEDATALEN);
strlcpy(beentry->st_sslstatus->ssl_cipher, be_tls_get_cipher(MyProcPort), NAMEDATALEN);
be_tls_get_peerdn_name(MyProcPort, beentry->st_sslstatus->ssl_clientdn, NAMEDATALEN);
}
else
{
beentry->st_ssl = false;
}
#else
beentry->st_ssl = false;
#endif
beentry->st_state = STATE_UNDEFINED;
beentry->st_appname[0] = '\0';
beentry->st_activity_raw[0] = '\0';
/* Also make sure the last byte in each string area is always 0 */
beentry->st_clienthostname[NAMEDATALEN - 1] = '\0';
beentry->st_appname[NAMEDATALEN - 1] = '\0';
beentry->st_activity_raw[pgstat_track_activity_query_size - 1] = '\0';
beentry->st_progress_command = PROGRESS_COMMAND_INVALID;
beentry->st_progress_command_target = InvalidOid;
2016-06-10 00:02:36 +02:00
/*
* we don't zero st_progress_param here to save cycles; nobody should
* examine it until st_progress_command has been set to something other
* than PROGRESS_COMMAND_INVALID
*/
pgstat_increment_changecount_after(beentry);
/* Update app name to current GUC setting */
if (application_name)
pgstat_report_appname(application_name);
}
/*
* Shut down a single backend's statistics reporting at process exit.
*
* Flush any remaining statistics counts out to the collector.
* Without this, operations triggered during backend exit (such as
* temp table deletions) won't be counted.
*
* Lastly, clear out our entry in the PgBackendStatus array.
*/
static void
pgstat_beshutdown_hook(int code, Datum arg)
{
volatile PgBackendStatus *beentry = MyBEEntry;
/*
2010-02-26 03:01:40 +01:00
* If we got as far as discovering our own database ID, we can report what
* we did to the collector. Otherwise, we'd be sending an invalid
* database ID, so forget it. (This means that accesses to pg_database
* during failed backend starts might never get counted.)
*/
if (OidIsValid(MyDatabaseId))
pgstat_report_stat(true);
/*
2006-10-04 02:30:14 +02:00
* Clear my status entry, following the protocol of bumping st_changecount
* before and after. We use a volatile pointer here to ensure the
* compiler doesn't try to get cute.
*/
pgstat_increment_changecount_before(beentry);
beentry->st_procpid = 0; /* mark invalid */
pgstat_increment_changecount_after(beentry);
}
/* ----------
* pgstat_report_activity() -
*
* Called from tcop/postgres.c to report what the backend is actually doing
* (but note cmd_str can be NULL for certain cases).
*
* All updates of the status entry follow the protocol of bumping
* st_changecount before and after. We use a volatile pointer here to
* ensure the compiler doesn't try to get cute.
* ----------
*/
void
pgstat_report_activity(BackendState state, const char *cmd_str)
{
volatile PgBackendStatus *beentry = MyBEEntry;
TimestampTz start_timestamp;
TimestampTz current_timestamp;
int len = 0;
TRACE_POSTGRESQL_STATEMENT_STATUS(cmd_str);
if (!beentry)
return;
if (!pgstat_track_activities)
{
if (beentry->st_state != STATE_DISABLED)
{
volatile PGPROC *proc = MyProc;
/*
* track_activities is disabled, but we last reported a
* non-disabled state. As our final update, change the state and
* clear fields we will not be updating anymore.
*/
pgstat_increment_changecount_before(beentry);
beentry->st_state = STATE_DISABLED;
beentry->st_state_start_timestamp = 0;
beentry->st_activity_raw[0] = '\0';
beentry->st_activity_start_timestamp = 0;
/* st_xact_start_timestamp and wait_event_info are also disabled */
beentry->st_xact_start_timestamp = 0;
proc->wait_event_info = 0;
pgstat_increment_changecount_after(beentry);
}
return;
}
/*
* To minimize the time spent modifying the entry, fetch all the needed
* data first.
*/
start_timestamp = GetCurrentStatementStartTimestamp();
if (cmd_str != NULL)
{
/*
* Compute length of to-be-stored string unaware of multi-byte
* characters. For speed reasons that'll get corrected on read, rather
* than computed every write.
*/
len = Min(strlen(cmd_str), pgstat_track_activity_query_size - 1);
}
current_timestamp = GetCurrentTimestamp();
/*
* Now update the status entry
*/
pgstat_increment_changecount_before(beentry);
beentry->st_state = state;
beentry->st_state_start_timestamp = current_timestamp;
if (cmd_str != NULL)
{
memcpy((char *) beentry->st_activity_raw, cmd_str, len);
beentry->st_activity_raw[len] = '\0';
beentry->st_activity_start_timestamp = start_timestamp;
}
pgstat_increment_changecount_after(beentry);
}
/*-----------
* pgstat_progress_start_command() -
*
* Set st_progress_command (and st_progress_command_target) in own backend
* entry. Also, zero-initialize st_progress_param array.
*-----------
*/
void
pgstat_progress_start_command(ProgressCommandType cmdtype, Oid relid)
{
volatile PgBackendStatus *beentry = MyBEEntry;
if (!beentry || !pgstat_track_activities)
return;
pgstat_increment_changecount_before(beentry);
beentry->st_progress_command = cmdtype;
beentry->st_progress_command_target = relid;
MemSet(&beentry->st_progress_param, 0, sizeof(beentry->st_progress_param));
pgstat_increment_changecount_after(beentry);
}
/*-----------
* pgstat_progress_update_param() -
*
* Update index'th member in st_progress_param[] of own backend entry.
*-----------
*/
void
pgstat_progress_update_param(int index, int64 val)
{
volatile PgBackendStatus *beentry = MyBEEntry;
Assert(index >= 0 && index < PGSTAT_NUM_PROGRESS_PARAM);
if (!beentry || !pgstat_track_activities)
return;
pgstat_increment_changecount_before(beentry);
beentry->st_progress_param[index] = val;
pgstat_increment_changecount_after(beentry);
}
/*-----------
* pgstat_progress_update_multi_param() -
*
* Update multiple members in st_progress_param[] of own backend entry.
* This is atomic; readers won't see intermediate states.
*-----------
*/
void
pgstat_progress_update_multi_param(int nparam, const int *index,
const int64 *val)
{
volatile PgBackendStatus *beentry = MyBEEntry;
2016-06-10 00:02:36 +02:00
int i;
if (!beentry || !pgstat_track_activities || nparam == 0)
return;
pgstat_increment_changecount_before(beentry);
for (i = 0; i < nparam; ++i)
{
Assert(index[i] >= 0 && index[i] < PGSTAT_NUM_PROGRESS_PARAM);
beentry->st_progress_param[index[i]] = val[i];
}
pgstat_increment_changecount_after(beentry);
}
/*-----------
* pgstat_progress_end_command() -
*
* Reset st_progress_command (and st_progress_command_target) in own backend
* entry. This signals the end of the command.
*-----------
*/
void
pgstat_progress_end_command(void)
{
volatile PgBackendStatus *beentry = MyBEEntry;
if (!beentry)
return;
if (!pgstat_track_activities
&& beentry->st_progress_command == PROGRESS_COMMAND_INVALID)
return;
pgstat_increment_changecount_before(beentry);
beentry->st_progress_command = PROGRESS_COMMAND_INVALID;
beentry->st_progress_command_target = InvalidOid;
pgstat_increment_changecount_after(beentry);
}
/* ----------
* pgstat_report_appname() -
*
* Called to update our application name.
* ----------
*/
void
pgstat_report_appname(const char *appname)
{
volatile PgBackendStatus *beentry = MyBEEntry;
int len;
if (!beentry)
return;
/* This should be unnecessary if GUC did its job, but be safe */
len = pg_mbcliplen(appname, strlen(appname), NAMEDATALEN - 1);
/*
* Update my status entry, following the protocol of bumping
* st_changecount before and after. We use a volatile pointer here to
* ensure the compiler doesn't try to get cute.
*/
pgstat_increment_changecount_before(beentry);
memcpy((char *) beentry->st_appname, appname, len);
beentry->st_appname[len] = '\0';
pgstat_increment_changecount_after(beentry);
}
/*
* Report current transaction start timestamp as the specified value.
* Zero means there is no active transaction.
*/
void
pgstat_report_xact_timestamp(TimestampTz tstamp)
{
volatile PgBackendStatus *beentry = MyBEEntry;
if (!pgstat_track_activities || !beentry)
return;
/*
* Update my status entry, following the protocol of bumping
2007-11-15 22:14:46 +01:00
* st_changecount before and after. We use a volatile pointer here to
* ensure the compiler doesn't try to get cute.
*/
pgstat_increment_changecount_before(beentry);
beentry->st_xact_start_timestamp = tstamp;
pgstat_increment_changecount_after(beentry);
}
/* ----------
* pgstat_read_current_status() -
*
* Copy the current contents of the PgBackendStatus array to local memory,
* if not already done in this transaction.
* ----------
*/
static void
pgstat_read_current_status(void)
{
volatile PgBackendStatus *beentry;
LocalPgBackendStatus *localtable;
LocalPgBackendStatus *localentry;
char *localappname,
*localclienthostname,
*localactivity;
#ifdef USE_SSL
PgBackendSSLStatus *localsslstatus;
#endif
int i;
Assert(!pgStatRunningInCollector);
if (localBackendStatusTable)
return; /* already done */
pgstat_setup_memcxt();
localtable = (LocalPgBackendStatus *)
MemoryContextAlloc(pgStatLocalContext,
sizeof(LocalPgBackendStatus) * NumBackendStatSlots);
localappname = (char *)
MemoryContextAlloc(pgStatLocalContext,
NAMEDATALEN * NumBackendStatSlots);
localclienthostname = (char *)
MemoryContextAlloc(pgStatLocalContext,
NAMEDATALEN * NumBackendStatSlots);
localactivity = (char *)
MemoryContextAlloc(pgStatLocalContext,
pgstat_track_activity_query_size * NumBackendStatSlots);
#ifdef USE_SSL
localsslstatus = (PgBackendSSLStatus *)
MemoryContextAlloc(pgStatLocalContext,
sizeof(PgBackendSSLStatus) * NumBackendStatSlots);
#endif
localNumBackends = 0;
beentry = BackendStatusArray;
localentry = localtable;
for (i = 1; i <= NumBackendStatSlots; i++)
{
/*
2006-10-04 02:30:14 +02:00
* Follow the protocol of retrying if st_changecount changes while we
* copy the entry, or if it's odd. (The check for odd is needed to
* cover the case where we are able to completely copy the entry while
* the source backend is between increment steps.) We use a volatile
* pointer here to ensure the compiler doesn't try to get cute.
*/
for (;;)
{
int before_changecount;
int after_changecount;
pgstat_save_changecount_before(beentry, before_changecount);
localentry->backendStatus.st_procpid = beentry->st_procpid;
if (localentry->backendStatus.st_procpid > 0)
{
memcpy(&localentry->backendStatus, (char *) beentry, sizeof(PgBackendStatus));
/*
* strcpy is safe even if the string is modified concurrently,
* because there's always a \0 at the end of the buffer.
*/
strcpy(localappname, (char *) beentry->st_appname);
localentry->backendStatus.st_appname = localappname;
strcpy(localclienthostname, (char *) beentry->st_clienthostname);
localentry->backendStatus.st_clienthostname = localclienthostname;
strcpy(localactivity, (char *) beentry->st_activity_raw);
localentry->backendStatus.st_activity_raw = localactivity;
localentry->backendStatus.st_ssl = beentry->st_ssl;
#ifdef USE_SSL
if (beentry->st_ssl)
{
memcpy(localsslstatus, beentry->st_sslstatus, sizeof(PgBackendSSLStatus));
localentry->backendStatus.st_sslstatus = localsslstatus;
}
#endif
}
pgstat_save_changecount_after(beentry, after_changecount);
if (before_changecount == after_changecount &&
(before_changecount & 1) == 0)
break;
/* Make sure we can break out of loop if stuck... */
CHECK_FOR_INTERRUPTS();
}
beentry++;
/* Only valid entries get included into the local array */
if (localentry->backendStatus.st_procpid > 0)
{
BackendIdGetTransactionIds(i,
&localentry->backend_xid,
&localentry->backend_xmin);
localentry++;
localappname += NAMEDATALEN;
localclienthostname += NAMEDATALEN;
localactivity += pgstat_track_activity_query_size;
#ifdef USE_SSL
localsslstatus++;
#endif
localNumBackends++;
}
}
/* Set the pointer only after completion of a valid table */
localBackendStatusTable = localtable;
}
/* ----------
* pgstat_get_wait_event_type() -
*
* Return a string representing the current wait event type, backend is
* waiting on.
*/
const char *
pgstat_get_wait_event_type(uint32 wait_event_info)
{
uint32 classId;
const char *event_type;
/* report process as not waiting. */
if (wait_event_info == 0)
return NULL;
classId = wait_event_info & 0xFF000000;
switch (classId)
{
Simplify LWLock tranche machinery by removing array_base/array_stride. array_base and array_stride were added so that we could identify the offset of an LWLock within a tranche, but this facility is only very marginally used apart from the main tranche. So, give every lock in the main tranche its own tranche ID and get rid of array_base, array_stride, and all that's attached. For debugging facilities (Trace_lwlocks and LWLOCK_STATS) print the pointer address of the LWLock using %p instead of the offset. This is arguably more useful, and certainly a lot cheaper. Drop the offset-within-tranche from the information reported to dtrace and from one can't-happen message inside lwlock.c. The main user-visible impact of this change is that pg_stat_activity will now report all waits for LWLocks as "LWLock" rather than reporting some as "LWLockTranche" and others as "LWLockNamed". The main motivation for this change is that the need to specify an array_base and an array_stride is awkward for parallel query. There is only a very limited supply of tranche IDs so we can't just keep allocating new ones, and if we try to use the same tranche IDs every time then we run into trouble when multiple parallel contexts are use simultaneously. So if we didn't get rid of this mechanism we'd have to make it even more complicated. By simplifying it in this way, we instead reduce the size of the generated code for lwlock.c by about 5%. Discussion: http://postgr.es/m/CA+TgmoYsFn6NUW1x0AZtupJGUAs1UDY4dJtCN47_Q6D0sP80PA@mail.gmail.com
2016-12-16 17:29:23 +01:00
case PG_WAIT_LWLOCK:
event_type = "LWLock";
break;
case PG_WAIT_LOCK:
event_type = "Lock";
break;
case PG_WAIT_BUFFER_PIN:
event_type = "BufferPin";
break;
case PG_WAIT_ACTIVITY:
event_type = "Activity";
break;
case PG_WAIT_CLIENT:
event_type = "Client";
break;
case PG_WAIT_EXTENSION:
event_type = "Extension";
break;
case PG_WAIT_IPC:
event_type = "IPC";
break;
case PG_WAIT_TIMEOUT:
event_type = "Timeout";
break;
case PG_WAIT_IO:
event_type = "IO";
break;
default:
event_type = "???";
break;
}
return event_type;
}
/* ----------
* pgstat_get_wait_event() -
*
* Return a string representing the current wait event, backend is
* waiting on.
*/
const char *
pgstat_get_wait_event(uint32 wait_event_info)
{
uint32 classId;
uint16 eventId;
const char *event_name;
/* report process as not waiting. */
if (wait_event_info == 0)
return NULL;
classId = wait_event_info & 0xFF000000;
eventId = wait_event_info & 0x0000FFFF;
switch (classId)
{
Simplify LWLock tranche machinery by removing array_base/array_stride. array_base and array_stride were added so that we could identify the offset of an LWLock within a tranche, but this facility is only very marginally used apart from the main tranche. So, give every lock in the main tranche its own tranche ID and get rid of array_base, array_stride, and all that's attached. For debugging facilities (Trace_lwlocks and LWLOCK_STATS) print the pointer address of the LWLock using %p instead of the offset. This is arguably more useful, and certainly a lot cheaper. Drop the offset-within-tranche from the information reported to dtrace and from one can't-happen message inside lwlock.c. The main user-visible impact of this change is that pg_stat_activity will now report all waits for LWLocks as "LWLock" rather than reporting some as "LWLockTranche" and others as "LWLockNamed". The main motivation for this change is that the need to specify an array_base and an array_stride is awkward for parallel query. There is only a very limited supply of tranche IDs so we can't just keep allocating new ones, and if we try to use the same tranche IDs every time then we run into trouble when multiple parallel contexts are use simultaneously. So if we didn't get rid of this mechanism we'd have to make it even more complicated. By simplifying it in this way, we instead reduce the size of the generated code for lwlock.c by about 5%. Discussion: http://postgr.es/m/CA+TgmoYsFn6NUW1x0AZtupJGUAs1UDY4dJtCN47_Q6D0sP80PA@mail.gmail.com
2016-12-16 17:29:23 +01:00
case PG_WAIT_LWLOCK:
event_name = GetLWLockIdentifier(classId, eventId);
break;
case PG_WAIT_LOCK:
event_name = GetLockNameFromTagType(eventId);
break;
case PG_WAIT_BUFFER_PIN:
event_name = "BufferPin";
break;
case PG_WAIT_ACTIVITY:
{
WaitEventActivity w = (WaitEventActivity) wait_event_info;
event_name = pgstat_get_wait_activity(w);
break;
}
case PG_WAIT_CLIENT:
{
WaitEventClient w = (WaitEventClient) wait_event_info;
event_name = pgstat_get_wait_client(w);
break;
}
case PG_WAIT_EXTENSION:
event_name = "Extension";
break;
case PG_WAIT_IPC:
{
WaitEventIPC w = (WaitEventIPC) wait_event_info;
event_name = pgstat_get_wait_ipc(w);
break;
}
case PG_WAIT_TIMEOUT:
{
WaitEventTimeout w = (WaitEventTimeout) wait_event_info;
event_name = pgstat_get_wait_timeout(w);
break;
}
case PG_WAIT_IO:
{
WaitEventIO w = (WaitEventIO) wait_event_info;
event_name = pgstat_get_wait_io(w);
break;
}
default:
event_name = "unknown wait event";
break;
}
return event_name;
}
/* ----------
* pgstat_get_wait_activity() -
*
* Convert WaitEventActivity to string.
* ----------
*/
static const char *
pgstat_get_wait_activity(WaitEventActivity w)
{
const char *event_name = "unknown wait event";
switch (w)
{
case WAIT_EVENT_ARCHIVER_MAIN:
event_name = "ArchiverMain";
break;
case WAIT_EVENT_AUTOVACUUM_MAIN:
event_name = "AutoVacuumMain";
break;
case WAIT_EVENT_BGWRITER_HIBERNATE:
event_name = "BgWriterHibernate";
break;
case WAIT_EVENT_BGWRITER_MAIN:
event_name = "BgWriterMain";
break;
case WAIT_EVENT_CHECKPOINTER_MAIN:
event_name = "CheckpointerMain";
break;
case WAIT_EVENT_LOGICAL_APPLY_MAIN:
event_name = "LogicalApplyMain";
break;
case WAIT_EVENT_LOGICAL_LAUNCHER_MAIN:
event_name = "LogicalLauncherMain";
break;
case WAIT_EVENT_PGSTAT_MAIN:
event_name = "PgStatMain";
break;
case WAIT_EVENT_RECOVERY_WAL_ALL:
event_name = "RecoveryWalAll";
break;
case WAIT_EVENT_RECOVERY_WAL_STREAM:
event_name = "RecoveryWalStream";
break;
case WAIT_EVENT_SYSLOGGER_MAIN:
event_name = "SysLoggerMain";
break;
case WAIT_EVENT_WAL_RECEIVER_MAIN:
event_name = "WalReceiverMain";
break;
case WAIT_EVENT_WAL_SENDER_MAIN:
event_name = "WalSenderMain";
break;
case WAIT_EVENT_WAL_WRITER_MAIN:
event_name = "WalWriterMain";
break;
/* no default case, so that compiler will warn */
}
return event_name;
}
/* ----------
* pgstat_get_wait_client() -
*
* Convert WaitEventClient to string.
* ----------
*/
static const char *
pgstat_get_wait_client(WaitEventClient w)
{
const char *event_name = "unknown wait event";
switch (w)
{
case WAIT_EVENT_CLIENT_READ:
event_name = "ClientRead";
break;
case WAIT_EVENT_CLIENT_WRITE:
event_name = "ClientWrite";
break;
case WAIT_EVENT_LIBPQWALRECEIVER_CONNECT:
event_name = "LibPQWalReceiverConnect";
break;
case WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE:
event_name = "LibPQWalReceiverReceive";
break;
case WAIT_EVENT_SSL_OPEN_SERVER:
event_name = "SSLOpenServer";
break;
case WAIT_EVENT_WAL_RECEIVER_WAIT_START:
event_name = "WalReceiverWaitStart";
break;
case WAIT_EVENT_WAL_SENDER_WAIT_WAL:
event_name = "WalSenderWaitForWAL";
break;
case WAIT_EVENT_WAL_SENDER_WRITE_DATA:
event_name = "WalSenderWriteData";
break;
/* no default case, so that compiler will warn */
}
return event_name;
}
/* ----------
* pgstat_get_wait_ipc() -
*
* Convert WaitEventIPC to string.
* ----------
*/
static const char *
pgstat_get_wait_ipc(WaitEventIPC w)
{
const char *event_name = "unknown wait event";
switch (w)
{
case WAIT_EVENT_BGWORKER_SHUTDOWN:
event_name = "BgWorkerShutdown";
break;
case WAIT_EVENT_BGWORKER_STARTUP:
event_name = "BgWorkerStartup";
break;
case WAIT_EVENT_BTREE_PAGE:
event_name = "BtreePage";
break;
case WAIT_EVENT_CLOG_GROUP_UPDATE:
event_name = "ClogGroupUpdate";
break;
case WAIT_EVENT_EXECUTE_GATHER:
event_name = "ExecuteGather";
break;
Add parallel-aware hash joins. Introduce parallel-aware hash joins that appear in EXPLAIN plans as Parallel Hash Join with Parallel Hash. While hash joins could already appear in parallel queries, they were previously always parallel-oblivious and had a partial subplan only on the outer side, meaning that the work of the inner subplan was duplicated in every worker. After this commit, the planner will consider using a partial subplan on the inner side too, using the Parallel Hash node to divide the work over the available CPU cores and combine its results in shared memory. If the join needs to be split into multiple batches in order to respect work_mem, then workers process different batches as much as possible and then work together on the remaining batches. The advantages of a parallel-aware hash join over a parallel-oblivious hash join used in a parallel query are that it: * avoids wasting memory on duplicated hash tables * avoids wasting disk space on duplicated batch files * divides the work of building the hash table over the CPUs One disadvantage is that there is some communication between the participating CPUs which might outweigh the benefits of parallelism in the case of small hash tables. This is avoided by the planner's existing reluctance to supply partial plans for small scans, but it may be necessary to estimate synchronization costs in future if that situation changes. Another is that outer batch 0 must be written to disk if multiple batches are required. A potential future advantage of parallel-aware hash joins is that right and full outer joins could be supported, since there is a single set of matched bits for each hashtable, but that is not yet implemented. A new GUC enable_parallel_hash is defined to control the feature, defaulting to on. Author: Thomas Munro Reviewed-By: Andres Freund, Robert Haas Tested-By: Rafia Sabih, Prabhat Sahu Discussion: https://postgr.es/m/CAEepm=2W=cOkiZxcg6qiFQP-dHUe09aqTrEMM7yJDrHMhDv_RA@mail.gmail.com https://postgr.es/m/CAEepm=37HKyJ4U6XOLi=JgfSHM3o6B-GaeO-6hkOmneTDkH+Uw@mail.gmail.com
2017-12-21 08:39:21 +01:00
case WAIT_EVENT_HASH_BATCH_ALLOCATING:
event_name = "Hash/Batch/Allocating";
break;
case WAIT_EVENT_HASH_BATCH_ELECTING:
event_name = "Hash/Batch/Electing";
break;
case WAIT_EVENT_HASH_BATCH_LOADING:
event_name = "Hash/Batch/Loading";
break;
case WAIT_EVENT_HASH_BUILD_ALLOCATING:
event_name = "Hash/Build/Allocating";
break;
case WAIT_EVENT_HASH_BUILD_ELECTING:
event_name = "Hash/Build/Electing";
break;
case WAIT_EVENT_HASH_BUILD_HASHING_INNER:
event_name = "Hash/Build/HashingInner";
break;
case WAIT_EVENT_HASH_BUILD_HASHING_OUTER:
event_name = "Hash/Build/HashingOuter";
break;
case WAIT_EVENT_HASH_GROW_BATCHES_ALLOCATING:
event_name = "Hash/GrowBatches/Allocating";
break;
case WAIT_EVENT_HASH_GROW_BATCHES_DECIDING:
event_name = "Hash/GrowBatches/Deciding";
break;
case WAIT_EVENT_HASH_GROW_BATCHES_ELECTING:
event_name = "Hash/GrowBatches/Electing";
break;
case WAIT_EVENT_HASH_GROW_BATCHES_FINISHING:
event_name = "Hash/GrowBatches/Finishing";
break;
case WAIT_EVENT_HASH_GROW_BATCHES_REPARTITIONING:
event_name = "Hash/GrowBatches/Repartitioning";
break;
case WAIT_EVENT_HASH_GROW_BUCKETS_ALLOCATING:
event_name = "Hash/GrowBuckets/Allocating";
break;
case WAIT_EVENT_HASH_GROW_BUCKETS_ELECTING:
event_name = "Hash/GrowBuckets/Electing";
break;
case WAIT_EVENT_HASH_GROW_BUCKETS_REINSERTING:
event_name = "Hash/GrowBuckets/Reinserting";
break;
case WAIT_EVENT_LOGICAL_SYNC_DATA:
event_name = "LogicalSyncData";
break;
case WAIT_EVENT_LOGICAL_SYNC_STATE_CHANGE:
event_name = "LogicalSyncStateChange";
break;
case WAIT_EVENT_MQ_INTERNAL:
event_name = "MessageQueueInternal";
break;
case WAIT_EVENT_MQ_PUT_MESSAGE:
event_name = "MessageQueuePutMessage";
break;
case WAIT_EVENT_MQ_RECEIVE:
event_name = "MessageQueueReceive";
break;
case WAIT_EVENT_MQ_SEND:
event_name = "MessageQueueSend";
break;
case WAIT_EVENT_PARALLEL_BITMAP_SCAN:
event_name = "ParallelBitmapScan";
break;
case WAIT_EVENT_PARALLEL_CREATE_INDEX_SCAN:
event_name = "ParallelCreateIndexScan";
break;
case WAIT_EVENT_PARALLEL_FINISH:
event_name = "ParallelFinish";
break;
case WAIT_EVENT_PROCARRAY_GROUP_UPDATE:
event_name = "ProcArrayGroupUpdate";
break;
case WAIT_EVENT_PROMOTE:
event_name = "Promote";
break;
case WAIT_EVENT_REPLICATION_ORIGIN_DROP:
event_name = "ReplicationOriginDrop";
break;
case WAIT_EVENT_REPLICATION_SLOT_DROP:
event_name = "ReplicationSlotDrop";
break;
case WAIT_EVENT_SAFE_SNAPSHOT:
event_name = "SafeSnapshot";
break;
case WAIT_EVENT_SYNC_REP:
event_name = "SyncRep";
break;
/* no default case, so that compiler will warn */
}
return event_name;
}
/* ----------
* pgstat_get_wait_timeout() -
*
* Convert WaitEventTimeout to string.
* ----------
*/
static const char *
pgstat_get_wait_timeout(WaitEventTimeout w)
{
const char *event_name = "unknown wait event";
switch (w)
{
case WAIT_EVENT_BASE_BACKUP_THROTTLE:
event_name = "BaseBackupThrottle";
break;
case WAIT_EVENT_PG_SLEEP:
event_name = "PgSleep";
break;
case WAIT_EVENT_RECOVERY_APPLY_DELAY:
event_name = "RecoveryApplyDelay";
break;
/* no default case, so that compiler will warn */
}
return event_name;
}
/* ----------
* pgstat_get_wait_io() -
*
* Convert WaitEventIO to string.
* ----------
*/
static const char *
pgstat_get_wait_io(WaitEventIO w)
{
const char *event_name = "unknown wait event";
switch (w)
{
case WAIT_EVENT_BUFFILE_READ:
event_name = "BufFileRead";
break;
case WAIT_EVENT_BUFFILE_WRITE:
event_name = "BufFileWrite";
break;
case WAIT_EVENT_CONTROL_FILE_READ:
event_name = "ControlFileRead";
break;
case WAIT_EVENT_CONTROL_FILE_SYNC:
event_name = "ControlFileSync";
break;
case WAIT_EVENT_CONTROL_FILE_SYNC_UPDATE:
event_name = "ControlFileSyncUpdate";
break;
case WAIT_EVENT_CONTROL_FILE_WRITE:
event_name = "ControlFileWrite";
break;
case WAIT_EVENT_CONTROL_FILE_WRITE_UPDATE:
event_name = "ControlFileWriteUpdate";
break;
case WAIT_EVENT_COPY_FILE_READ:
event_name = "CopyFileRead";
break;
case WAIT_EVENT_COPY_FILE_WRITE:
event_name = "CopyFileWrite";
break;
case WAIT_EVENT_DATA_FILE_EXTEND:
event_name = "DataFileExtend";
break;
case WAIT_EVENT_DATA_FILE_FLUSH:
event_name = "DataFileFlush";
break;
case WAIT_EVENT_DATA_FILE_IMMEDIATE_SYNC:
event_name = "DataFileImmediateSync";
break;
case WAIT_EVENT_DATA_FILE_PREFETCH:
event_name = "DataFilePrefetch";
break;
case WAIT_EVENT_DATA_FILE_READ:
event_name = "DataFileRead";
break;
case WAIT_EVENT_DATA_FILE_SYNC:
event_name = "DataFileSync";
break;
case WAIT_EVENT_DATA_FILE_TRUNCATE:
event_name = "DataFileTruncate";
break;
case WAIT_EVENT_DATA_FILE_WRITE:
event_name = "DataFileWrite";
break;
case WAIT_EVENT_DSM_FILL_ZERO_WRITE:
event_name = "DSMFillZeroWrite";
break;
case WAIT_EVENT_LOCK_FILE_ADDTODATADIR_READ:
event_name = "LockFileAddToDataDirRead";
break;
case WAIT_EVENT_LOCK_FILE_ADDTODATADIR_SYNC:
event_name = "LockFileAddToDataDirSync";
break;
case WAIT_EVENT_LOCK_FILE_ADDTODATADIR_WRITE:
event_name = "LockFileAddToDataDirWrite";
break;
case WAIT_EVENT_LOCK_FILE_CREATE_READ:
event_name = "LockFileCreateRead";
break;
case WAIT_EVENT_LOCK_FILE_CREATE_SYNC:
event_name = "LockFileCreateSync";
break;
case WAIT_EVENT_LOCK_FILE_CREATE_WRITE:
event_name = "LockFileCreateWRITE";
break;
case WAIT_EVENT_LOCK_FILE_RECHECKDATADIR_READ:
event_name = "LockFileReCheckDataDirRead";
break;
case WAIT_EVENT_LOGICAL_REWRITE_CHECKPOINT_SYNC:
event_name = "LogicalRewriteCheckpointSync";
break;
case WAIT_EVENT_LOGICAL_REWRITE_MAPPING_SYNC:
event_name = "LogicalRewriteMappingSync";
break;
case WAIT_EVENT_LOGICAL_REWRITE_MAPPING_WRITE:
event_name = "LogicalRewriteMappingWrite";
break;
case WAIT_EVENT_LOGICAL_REWRITE_SYNC:
event_name = "LogicalRewriteSync";
break;
case WAIT_EVENT_LOGICAL_REWRITE_TRUNCATE:
event_name = "LogicalRewriteTruncate";
break;
case WAIT_EVENT_LOGICAL_REWRITE_WRITE:
event_name = "LogicalRewriteWrite";
break;
case WAIT_EVENT_RELATION_MAP_READ:
event_name = "RelationMapRead";
break;
case WAIT_EVENT_RELATION_MAP_SYNC:
event_name = "RelationMapSync";
break;
case WAIT_EVENT_RELATION_MAP_WRITE:
event_name = "RelationMapWrite";
break;
case WAIT_EVENT_REORDER_BUFFER_READ:
event_name = "ReorderBufferRead";
break;
case WAIT_EVENT_REORDER_BUFFER_WRITE:
event_name = "ReorderBufferWrite";
break;
case WAIT_EVENT_REORDER_LOGICAL_MAPPING_READ:
event_name = "ReorderLogicalMappingRead";
break;
case WAIT_EVENT_REPLICATION_SLOT_READ:
event_name = "ReplicationSlotRead";
break;
case WAIT_EVENT_REPLICATION_SLOT_RESTORE_SYNC:
event_name = "ReplicationSlotRestoreSync";
break;
case WAIT_EVENT_REPLICATION_SLOT_SYNC:
event_name = "ReplicationSlotSync";
break;
case WAIT_EVENT_REPLICATION_SLOT_WRITE:
event_name = "ReplicationSlotWrite";
break;
case WAIT_EVENT_SLRU_FLUSH_SYNC:
event_name = "SLRUFlushSync";
break;
case WAIT_EVENT_SLRU_READ:
event_name = "SLRURead";
break;
case WAIT_EVENT_SLRU_SYNC:
event_name = "SLRUSync";
break;
case WAIT_EVENT_SLRU_WRITE:
event_name = "SLRUWrite";
break;
case WAIT_EVENT_SNAPBUILD_READ:
event_name = "SnapbuildRead";
break;
case WAIT_EVENT_SNAPBUILD_SYNC:
event_name = "SnapbuildSync";
break;
case WAIT_EVENT_SNAPBUILD_WRITE:
event_name = "SnapbuildWrite";
break;
case WAIT_EVENT_TIMELINE_HISTORY_FILE_SYNC:
event_name = "TimelineHistoryFileSync";
break;
case WAIT_EVENT_TIMELINE_HISTORY_FILE_WRITE:
event_name = "TimelineHistoryFileWrite";
break;
case WAIT_EVENT_TIMELINE_HISTORY_READ:
event_name = "TimelineHistoryRead";
break;
case WAIT_EVENT_TIMELINE_HISTORY_SYNC:
event_name = "TimelineHistorySync";
break;
case WAIT_EVENT_TIMELINE_HISTORY_WRITE:
event_name = "TimelineHistoryWrite";
break;
case WAIT_EVENT_TWOPHASE_FILE_READ:
event_name = "TwophaseFileRead";
break;
case WAIT_EVENT_TWOPHASE_FILE_SYNC:
event_name = "TwophaseFileSync";
break;
case WAIT_EVENT_TWOPHASE_FILE_WRITE:
event_name = "TwophaseFileWrite";
break;
case WAIT_EVENT_WALSENDER_TIMELINE_HISTORY_READ:
event_name = "WALSenderTimelineHistoryRead";
break;
case WAIT_EVENT_WAL_BOOTSTRAP_SYNC:
event_name = "WALBootstrapSync";
break;
case WAIT_EVENT_WAL_BOOTSTRAP_WRITE:
event_name = "WALBootstrapWrite";
break;
case WAIT_EVENT_WAL_COPY_READ:
event_name = "WALCopyRead";
break;
case WAIT_EVENT_WAL_COPY_SYNC:
event_name = "WALCopySync";
break;
case WAIT_EVENT_WAL_COPY_WRITE:
event_name = "WALCopyWrite";
break;
case WAIT_EVENT_WAL_INIT_SYNC:
event_name = "WALInitSync";
break;
case WAIT_EVENT_WAL_INIT_WRITE:
event_name = "WALInitWrite";
break;
case WAIT_EVENT_WAL_READ:
event_name = "WALRead";
break;
case WAIT_EVENT_WAL_SYNC:
event_name = "WALSync";
break;
case WAIT_EVENT_WAL_SYNC_METHOD_ASSIGN:
event_name = "WALSyncMethodAssign";
break;
case WAIT_EVENT_WAL_WRITE:
event_name = "WALWrite";
break;
/* no default case, so that compiler will warn */
}
return event_name;
}
/* ----------
* pgstat_get_backend_current_activity() -
*
* Return a string representing the current activity of the backend with
* the specified PID. This looks directly at the BackendStatusArray,
* and so will provide current information regardless of the age of our
* transaction's snapshot of the status array.
*
* It is the caller's responsibility to invoke this only for backends whose
* state is expected to remain stable while the result is in use. The
* only current use is in deadlock reporting, where we can expect that
* the target backend is blocked on a lock. (There are corner cases
* where the target's wait could get aborted while we are looking at it,
* but the very worst consequence is to return a pointer to a string
* that's been changed, so we won't worry too much.)
*
* Note: return strings for special cases match pg_stat_get_backend_activity.
* ----------
*/
const char *
pgstat_get_backend_current_activity(int pid, bool checkUser)
{
PgBackendStatus *beentry;
int i;
beentry = BackendStatusArray;
for (i = 1; i <= MaxBackends; i++)
{
/*
* Although we expect the target backend's entry to be stable, that
* doesn't imply that anyone else's is. To avoid identifying the
* wrong backend, while we check for a match to the desired PID we
* must follow the protocol of retrying if st_changecount changes
* while we examine the entry, or if it's odd. (This might be
* unnecessary, since fetching or storing an int is almost certainly
* atomic, but let's play it safe.) We use a volatile pointer here to
* ensure the compiler doesn't try to get cute.
*/
volatile PgBackendStatus *vbeentry = beentry;
bool found;
for (;;)
{
int before_changecount;
int after_changecount;
pgstat_save_changecount_before(vbeentry, before_changecount);
found = (vbeentry->st_procpid == pid);
pgstat_save_changecount_after(vbeentry, after_changecount);
if (before_changecount == after_changecount &&
(before_changecount & 1) == 0)
break;
/* Make sure we can break out of loop if stuck... */
CHECK_FOR_INTERRUPTS();
}
if (found)
{
/* Now it is safe to use the non-volatile pointer */
if (checkUser && !superuser() && beentry->st_userid != GetUserId())
return "<insufficient privilege>";
else if (*(beentry->st_activity_raw) == '\0')
return "<command string not enabled>";
else
{
/* this'll leak a bit of memory, but that seems acceptable */
return pgstat_clip_activity(beentry->st_activity_raw);
}
}
beentry++;
}
/* If we get here, caller is in error ... */
return "<backend information not available>";
}
/* ----------
* pgstat_get_crashed_backend_activity() -
*
* Return a string representing the current activity of the backend with
* the specified PID. Like the function above, but reads shared memory with
* the expectation that it may be corrupt. On success, copy the string
* into the "buffer" argument and return that pointer. On failure,
* return NULL.
*
* This function is only intended to be used by the postmaster to report the
* query that crashed a backend. In particular, no attempt is made to
* follow the correct concurrency protocol when accessing the
* BackendStatusArray. But that's OK, in the worst case we'll return a
* corrupted message. We also must take care not to trip on ereport(ERROR).
* ----------
*/
const char *
pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
{
volatile PgBackendStatus *beentry;
int i;
beentry = BackendStatusArray;
/*
* We probably shouldn't get here before shared memory has been set up,
* but be safe.
*/
if (beentry == NULL || BackendActivityBuffer == NULL)
return NULL;
for (i = 1; i <= MaxBackends; i++)
{
if (beentry->st_procpid == pid)
{
/* Read pointer just once, so it can't change after validation */
const char *activity = beentry->st_activity_raw;
const char *activity_last;
/*
* We mustn't access activity string before we verify that it
* falls within the BackendActivityBuffer. To make sure that the
* entire string including its ending is contained within the
* buffer, subtract one activity length from the buffer size.
*/
activity_last = BackendActivityBuffer + BackendActivityBufferSize
- pgstat_track_activity_query_size;
if (activity < BackendActivityBuffer ||
activity > activity_last)
return NULL;
/* If no string available, no point in a report */
if (activity[0] == '\0')
return NULL;
/*
* Copy only ASCII-safe characters so we don't run into encoding
* problems when reporting the message; and be sure not to run off
* the end of memory. As only ASCII characters are reported, it
* doesn't seem necessary to perform multibyte aware clipping.
*/
ascii_safe_strlcpy(buffer, activity,
Min(buflen, pgstat_track_activity_query_size));
return buffer;
}
beentry++;
}
/* PID not found */
return NULL;
}
const char *
pgstat_get_backend_desc(BackendType backendType)
{
const char *backendDesc = "unknown process type";
switch (backendType)
{
case B_AUTOVAC_LAUNCHER:
backendDesc = "autovacuum launcher";
break;
case B_AUTOVAC_WORKER:
backendDesc = "autovacuum worker";
break;
case B_BACKEND:
backendDesc = "client backend";
break;
case B_BG_WORKER:
backendDesc = "background worker";
break;
case B_BG_WRITER:
backendDesc = "background writer";
break;
case B_CHECKPOINTER:
backendDesc = "checkpointer";
break;
case B_STARTUP:
backendDesc = "startup";
break;
case B_WAL_RECEIVER:
backendDesc = "walreceiver";
break;
case B_WAL_SENDER:
backendDesc = "walsender";
break;
case B_WAL_WRITER:
backendDesc = "walwriter";
break;
}
return backendDesc;
}
/* ------------------------------------------------------------
* Local support functions follow
* ------------------------------------------------------------
*/
/* ----------
* pgstat_setheader() -
*
* Set common header fields in a statistics message
* ----------
*/
static void
pgstat_setheader(PgStat_MsgHdr *hdr, StatMsgType mtype)
{
hdr->m_type = mtype;
}
/* ----------
* pgstat_send() -
*
* Send out one statistics message to the collector
* ----------
*/
static void
pgstat_send(void *msg, int len)
{
int rc;
if (pgStatSock == PGINVALID_SOCKET)
return;
((PgStat_MsgHdr *) msg)->m_size = len;
/* We'll retry after EINTR, but ignore all other failures */
do
{
rc = send(pgStatSock, msg, len, 0);
} while (rc < 0 && errno == EINTR);
#ifdef USE_ASSERT_CHECKING
/* In debug builds, log send failures ... */
if (rc < 0)
elog(LOG, "could not send to statistics collector: %m");
#endif
}
/* ----------
* pgstat_send_archiver() -
*
* Tell the collector about the WAL file that we successfully
* archived or failed to archive.
* ----------
*/
void
pgstat_send_archiver(const char *xlog, bool failed)
{
PgStat_MsgArchiver msg;
/*
* Prepare and send the message
*/
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_ARCHIVER);
msg.m_failed = failed;
StrNCpy(msg.m_xlog, xlog, sizeof(msg.m_xlog));
msg.m_timestamp = GetCurrentTimestamp();
pgstat_send(&msg, sizeof(msg));
}
/* ----------
* pgstat_send_bgwriter() -
*
2007-11-15 22:14:46 +01:00
* Send bgwriter statistics to the collector
* ----------
*/
void
pgstat_send_bgwriter(void)
{
/* We assume this initializes to zeroes */
static const PgStat_MsgBgWriter all_zeroes;
/*
2007-11-15 22:14:46 +01:00
* This function can be called even if nothing at all has happened. In
* this case, avoid sending a completely empty message to the stats
* collector.
*/
if (memcmp(&BgWriterStats, &all_zeroes, sizeof(PgStat_MsgBgWriter)) == 0)
return;
/*
* Prepare and send the message
*/
pgstat_setheader(&BgWriterStats.m_hdr, PGSTAT_MTYPE_BGWRITER);
pgstat_send(&BgWriterStats, sizeof(BgWriterStats));
/*
* Clear out the statistics buffer, so it can be re-used.
*/
MemSet(&BgWriterStats, 0, sizeof(BgWriterStats));
}
/* ----------
* PgstatCollectorMain() -
*
* Start up the statistics collector process. This is the body of the
* postmaster child process.
*
* The argc/argv parameters are valid only in EXEC_BACKEND case.
* ----------
*/
NON_EXEC_STATIC void
PgstatCollectorMain(int argc, char *argv[])
{
int len;
PgStat_Msg msg;
int wr;
/*
* Ignore all signals usually bound to some action in the postmaster,
* except SIGHUP and SIGQUIT. Note we don't need a SIGUSR1 handler to
* support latch operations, because we only use a local latch.
*/
pqsignal(SIGHUP, pgstat_sighup_handler);
pqsignal(SIGINT, SIG_IGN);
pqsignal(SIGTERM, SIG_IGN);
pqsignal(SIGQUIT, pgstat_exit);
pqsignal(SIGALRM, SIG_IGN);
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR1, SIG_IGN);
pqsignal(SIGUSR2, SIG_IGN);
/* Reset some signals that are accepted by postmaster but not here */
pqsignal(SIGCHLD, SIG_DFL);
PG_SETMASK(&UnBlockSig);
/*
* Identify myself via ps
*/
init_ps_display("stats collector", "", "", "");
/*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* Read in existing stats files or initialize the stats to zero.
*/
pgStatRunningInCollector = true;
pgStatDBHash = pgstat_read_statsfiles(InvalidOid, true, true);
/*
* Loop to process messages until we get SIGQUIT or detect ungraceful
* death of our parent postmaster.
*
* For performance reasons, we don't want to do ResetLatch/WaitLatch after
* every message; instead, do that only after a recv() fails to obtain a
* message. (This effectively means that if backends are sending us stuff
* like mad, we won't notice postmaster death until things slack off a
* bit; which seems fine.) To do that, we have an inner loop that
* iterates as long as recv() succeeds. We do recognize got_SIGHUP inside
* the inner loop, which means that such interrupts will get serviced but
* the latch won't get cleared until next time there is a break in the
* action.
*/
for (;;)
{
/* Clear any already-pending wakeups */
ResetLatch(MyLatch);
/*
* Quit if we get SIGQUIT from the postmaster.
*/
if (need_exit)
break;
/*
* Inner loop iterates as long as we keep getting messages, or until
* need_exit becomes set.
*/
while (!need_exit)
{
/*
* Reload configuration if we got SIGHUP from the postmaster.
*/
if (got_SIGHUP)
{
got_SIGHUP = false;
ProcessConfigFile(PGC_SIGHUP);
}
/*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* Write the stats file(s) if a new request has arrived that is
* not satisfied by existing file(s).
*/
if (pgstat_write_statsfile_needed())
pgstat_write_statsfiles(false, false);
/*
* Try to receive and process a message. This will not block,
* since the socket is set to non-blocking mode.
*
* XXX On Windows, we have to force pgwin32_recv to cooperate,
* despite the previous use of pg_set_noblock() on the socket.
* This is extremely broken and should be fixed someday.
*/
#ifdef WIN32
pgwin32_noblock = 1;
#endif
len = recv(pgStatSock, (char *) &msg,
sizeof(PgStat_Msg), 0);
#ifdef WIN32
pgwin32_noblock = 0;
#endif
if (len < 0)
{
if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
break; /* out of inner loop */
ereport(ERROR,
(errcode_for_socket_access(),
errmsg("could not read statistics message: %m")));
}
/*
* We ignore messages that are smaller than our common header
*/
if (len < sizeof(PgStat_MsgHdr))
continue;
/*
* The received length must match the length in the header
*/
if (msg.msg_hdr.m_size != len)
continue;
/*
* O.K. - we accept this message. Process it.
*/
switch (msg.msg_hdr.m_type)
{
case PGSTAT_MTYPE_DUMMY:
break;
case PGSTAT_MTYPE_INQUIRY:
pgstat_recv_inquiry((PgStat_MsgInquiry *) &msg, len);
break;
case PGSTAT_MTYPE_TABSTAT:
pgstat_recv_tabstat((PgStat_MsgTabstat *) &msg, len);
break;
case PGSTAT_MTYPE_TABPURGE:
pgstat_recv_tabpurge((PgStat_MsgTabpurge *) &msg, len);
break;
case PGSTAT_MTYPE_DROPDB:
pgstat_recv_dropdb((PgStat_MsgDropdb *) &msg, len);
break;
case PGSTAT_MTYPE_RESETCOUNTER:
pgstat_recv_resetcounter((PgStat_MsgResetcounter *) &msg,
len);
break;
case PGSTAT_MTYPE_RESETSHAREDCOUNTER:
pgstat_recv_resetsharedcounter(
(PgStat_MsgResetsharedcounter *) &msg,
2010-02-26 03:01:40 +01:00
len);
break;
case PGSTAT_MTYPE_RESETSINGLECOUNTER:
pgstat_recv_resetsinglecounter(
(PgStat_MsgResetsinglecounter *) &msg,
2010-02-26 03:01:40 +01:00
len);
break;
case PGSTAT_MTYPE_AUTOVAC_START:
pgstat_recv_autovac((PgStat_MsgAutovacStart *) &msg, len);
break;
case PGSTAT_MTYPE_VACUUM:
pgstat_recv_vacuum((PgStat_MsgVacuum *) &msg, len);
break;
case PGSTAT_MTYPE_ANALYZE:
pgstat_recv_analyze((PgStat_MsgAnalyze *) &msg, len);
break;
case PGSTAT_MTYPE_ARCHIVER:
pgstat_recv_archiver((PgStat_MsgArchiver *) &msg, len);
break;
case PGSTAT_MTYPE_BGWRITER:
pgstat_recv_bgwriter((PgStat_MsgBgWriter *) &msg, len);
break;
case PGSTAT_MTYPE_FUNCSTAT:
pgstat_recv_funcstat((PgStat_MsgFuncstat *) &msg, len);
break;
case PGSTAT_MTYPE_FUNCPURGE:
pgstat_recv_funcpurge((PgStat_MsgFuncpurge *) &msg, len);
break;
case PGSTAT_MTYPE_RECOVERYCONFLICT:
pgstat_recv_recoveryconflict((PgStat_MsgRecoveryConflict *) &msg, len);
break;
case PGSTAT_MTYPE_DEADLOCK:
pgstat_recv_deadlock((PgStat_MsgDeadlock *) &msg, len);
break;
case PGSTAT_MTYPE_TEMPFILE:
pgstat_recv_tempfile((PgStat_MsgTempFile *) &msg, len);
break;
default:
break;
}
} /* end of inner message-processing loop */
/* Sleep until there's something to do */
#ifndef WIN32
wr = WaitLatchOrSocket(MyLatch,
WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE,
pgStatSock, -1L,
WAIT_EVENT_PGSTAT_MAIN);
#else
/*
* Windows, at least in its Windows Server 2003 R2 incarnation,
* sometimes loses FD_READ events. Waking up and retrying the recv()
* fixes that, so don't sleep indefinitely. This is a crock of the
* first water, but until somebody wants to debug exactly what's
* happening there, this is the best we can do. The two-second
* timeout matches our pre-9.2 behavior, and needs to be short enough
* to not provoke "using stale statistics" complaints from
* backend_read_statsfile.
*/
wr = WaitLatchOrSocket(MyLatch,
WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE | WL_TIMEOUT,
pgStatSock,
2 * 1000L /* msec */ ,
WAIT_EVENT_PGSTAT_MAIN);
#endif
/*
* Emergency bailout if postmaster has died. This is to avoid the
* necessity for manual cleanup of all postmaster children.
*/
if (wr & WL_POSTMASTER_DEATH)
break;
} /* end of outer loop */
/*
* Save the final stats to reuse at next startup.
*/
pgstat_write_statsfiles(true, true);
exit(0);
}
/* SIGQUIT signal handler for collector process */
static void
pgstat_exit(SIGNAL_ARGS)
{
int save_errno = errno;
need_exit = true;
SetLatch(MyLatch);
errno = save_errno;
}
/* SIGHUP handler for collector process */
static void
pgstat_sighup_handler(SIGNAL_ARGS)
{
int save_errno = errno;
got_SIGHUP = true;
SetLatch(MyLatch);
errno = save_errno;
}
/*
* Subroutine to clear stats in a database entry
*
* Tables and functions hashes are initialized to empty.
*/
static void
reset_dbentry_counters(PgStat_StatDBEntry *dbentry)
{
HASHCTL hash_ctl;
dbentry->n_xact_commit = 0;
dbentry->n_xact_rollback = 0;
dbentry->n_blocks_fetched = 0;
dbentry->n_blocks_hit = 0;
dbentry->n_tuples_returned = 0;
dbentry->n_tuples_fetched = 0;
dbentry->n_tuples_inserted = 0;
dbentry->n_tuples_updated = 0;
dbentry->n_tuples_deleted = 0;
dbentry->last_autovac_time = 0;
dbentry->n_conflict_tablespace = 0;
dbentry->n_conflict_lock = 0;
dbentry->n_conflict_snapshot = 0;
dbentry->n_conflict_bufferpin = 0;
dbentry->n_conflict_startup_deadlock = 0;
dbentry->n_temp_files = 0;
dbentry->n_temp_bytes = 0;
dbentry->n_deadlocks = 0;
dbentry->n_block_read_time = 0;
dbentry->n_block_write_time = 0;
dbentry->stat_reset_timestamp = GetCurrentTimestamp();
dbentry->stats_timestamp = 0;
memset(&hash_ctl, 0, sizeof(hash_ctl));
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(PgStat_StatTabEntry);
dbentry->tables = hash_create("Per-database table",
PGSTAT_TAB_HASH_SIZE,
&hash_ctl,
Improve hash_create's API for selecting simple-binary-key hash functions. Previously, if you wanted anything besides C-string hash keys, you had to specify a custom hashing function to hash_create(). Nearly all such callers were specifying tag_hash or oid_hash; which is tedious, and rather error-prone, since a caller could easily miss the opportunity to optimize by using hash_uint32 when appropriate. Replace this with a design whereby callers using simple binary-data keys just specify HASH_BLOBS and don't need to mess with specific support functions. hash_create() itself will take care of optimizing when the key size is four bytes. This nets out saving a few hundred bytes of code space, and offers a measurable performance improvement in tidbitmap.c (which was not exploiting the opportunity to use hash_uint32 for its 4-byte keys). There might be some wins elsewhere too, I didn't analyze closely. In future we could look into offering a similar optimized hashing function for 8-byte keys. Under this design that could be done in a centralized and machine-independent fashion, whereas getting it right for keys of platform-dependent sizes would've been notationally painful before. For the moment, the old way still works fine, so as not to break source code compatibility for loadable modules. Eventually we might want to remove tag_hash and friends from the exported API altogether, since there's no real need for them to be explicitly referenced from outside dynahash.c. Teodor Sigaev and Tom Lane
2014-12-18 19:36:29 +01:00
HASH_ELEM | HASH_BLOBS);
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(PgStat_StatFuncEntry);
dbentry->functions = hash_create("Per-database function",
PGSTAT_FUNCTION_HASH_SIZE,
&hash_ctl,
Improve hash_create's API for selecting simple-binary-key hash functions. Previously, if you wanted anything besides C-string hash keys, you had to specify a custom hashing function to hash_create(). Nearly all such callers were specifying tag_hash or oid_hash; which is tedious, and rather error-prone, since a caller could easily miss the opportunity to optimize by using hash_uint32 when appropriate. Replace this with a design whereby callers using simple binary-data keys just specify HASH_BLOBS and don't need to mess with specific support functions. hash_create() itself will take care of optimizing when the key size is four bytes. This nets out saving a few hundred bytes of code space, and offers a measurable performance improvement in tidbitmap.c (which was not exploiting the opportunity to use hash_uint32 for its 4-byte keys). There might be some wins elsewhere too, I didn't analyze closely. In future we could look into offering a similar optimized hashing function for 8-byte keys. Under this design that could be done in a centralized and machine-independent fashion, whereas getting it right for keys of platform-dependent sizes would've been notationally painful before. For the moment, the old way still works fine, so as not to break source code compatibility for loadable modules. Eventually we might want to remove tag_hash and friends from the exported API altogether, since there's no real need for them to be explicitly referenced from outside dynahash.c. Teodor Sigaev and Tom Lane
2014-12-18 19:36:29 +01:00
HASH_ELEM | HASH_BLOBS);
}
/*
* Lookup the hash table entry for the specified database. If no hash
* table entry exists, initialize it, if the create parameter is true.
* Else, return NULL.
*/
static PgStat_StatDBEntry *
pgstat_get_db_entry(Oid databaseid, bool create)
{
PgStat_StatDBEntry *result;
2005-10-15 04:49:52 +02:00
bool found;
HASHACTION action = (create ? HASH_ENTER : HASH_FIND);
/* Lookup or create the hash table entry for this database */
result = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
&databaseid,
action, &found);
if (!create && !found)
return NULL;
/*
* If not found, initialize the new one. This creates empty hash tables
* for tables and functions, too.
*/
if (!found)
reset_dbentry_counters(result);
return result;
}
/*
* Lookup the hash table entry for the specified table. If no hash
* table entry exists, initialize it, if the create parameter is true.
* Else, return NULL.
*/
static PgStat_StatTabEntry *
pgstat_get_tab_entry(PgStat_StatDBEntry *dbentry, Oid tableoid, bool create)
{
PgStat_StatTabEntry *result;
bool found;
HASHACTION action = (create ? HASH_ENTER : HASH_FIND);
/* Lookup or create the hash table entry for this table */
result = (PgStat_StatTabEntry *) hash_search(dbentry->tables,
&tableoid,
action, &found);
if (!create && !found)
return NULL;
/* If not found, initialize the new one. */
if (!found)
{
result->numscans = 0;
result->tuples_returned = 0;
result->tuples_fetched = 0;
result->tuples_inserted = 0;
result->tuples_updated = 0;
result->tuples_deleted = 0;
result->tuples_hot_updated = 0;
result->n_live_tuples = 0;
result->n_dead_tuples = 0;
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
result->changes_since_analyze = 0;
result->blocks_fetched = 0;
result->blocks_hit = 0;
result->vacuum_timestamp = 0;
result->vacuum_count = 0;
result->autovac_vacuum_timestamp = 0;
result->autovac_vacuum_count = 0;
result->analyze_timestamp = 0;
result->analyze_count = 0;
result->autovac_analyze_timestamp = 0;
result->autovac_analyze_count = 0;
}
return result;
}
/* ----------
* pgstat_write_statsfiles() -
* Write the global statistics file, as well as requested DB files.
*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* 'permanent' specifies writing to the permanent files not temporary ones.
* When true (happens only when the collector is shutting down), also remove
* the temporary files so that backends starting up under a new postmaster
* can't read old data before the new collector is ready.
*
* When 'allDbs' is false, only the requested databases (listed in
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* pending_write_requests) will be written; otherwise, all databases
* will be written.
* ----------
*/
static void
pgstat_write_statsfiles(bool permanent, bool allDbs)
{
HASH_SEQ_STATUS hstat;
PgStat_StatDBEntry *dbentry;
FILE *fpout;
int32 format_id;
const char *tmpfile = permanent ? PGSTAT_STAT_PERMANENT_TMPFILE : pgstat_stat_tmpname;
const char *statfile = permanent ? PGSTAT_STAT_PERMANENT_FILENAME : pgstat_stat_filename;
int rc;
elog(DEBUG2, "writing stats file \"%s\"", statfile);
/*
* Open the statistics temp file to write out the current values.
*/
fpout = AllocateFile(tmpfile, PG_BINARY_W);
if (fpout == NULL)
{
ereport(LOG,
(errcode_for_file_access(),
2005-10-15 04:49:52 +02:00
errmsg("could not open temporary statistics file \"%s\": %m",
tmpfile)));
return;
}
/*
* Set the timestamp of the stats file.
*/
globalStats.stats_timestamp = GetCurrentTimestamp();
/*
* Write the file header --- currently just a format ID.
*/
format_id = PGSTAT_FILE_FORMAT_ID;
rc = fwrite(&format_id, sizeof(format_id), 1, fpout);
(void) rc; /* we'll check for error with ferror */
/*
* Write global stats struct
*/
rc = fwrite(&globalStats, sizeof(globalStats), 1, fpout);
(void) rc; /* we'll check for error with ferror */
/*
* Write archiver stats struct
*/
rc = fwrite(&archiverStats, sizeof(archiverStats), 1, fpout);
(void) rc; /* we'll check for error with ferror */
/*
* Walk through the database table.
*/
hash_seq_init(&hstat, pgStatDBHash);
while ((dbentry = (PgStat_StatDBEntry *) hash_seq_search(&hstat)) != NULL)
{
/*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* Write out the table and function stats for this DB into the
* appropriate per-DB stat file, if required.
*/
if (allDbs || pgstat_db_requested(dbentry->databaseid))
{
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
/* Make DB's timestamp consistent with the global stats */
dbentry->stats_timestamp = globalStats.stats_timestamp;
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
pgstat_write_db_statsfile(dbentry, permanent);
}
/*
* Write out the DB entry. We don't write the tables or functions
* pointers, since they're of no use to any other process.
*/
fputc('D', fpout);
rc = fwrite(dbentry, offsetof(PgStat_StatDBEntry, tables), 1, fpout);
(void) rc; /* we'll check for error with ferror */
}
/*
* No more output to be done. Close the temp file and replace the old
* pgstat.stat with it. The ferror() check replaces testing for error
* after each individual fputc or fwrite above.
*/
fputc('E', fpout);
if (ferror(fpout))
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write temporary statistics file \"%s\": %m",
tmpfile)));
FreeFile(fpout);
unlink(tmpfile);
}
else if (FreeFile(fpout) < 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not close temporary statistics file \"%s\": %m",
tmpfile)));
unlink(tmpfile);
}
else if (rename(tmpfile, statfile) < 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not rename temporary statistics file \"%s\" to \"%s\": %m",
tmpfile, statfile)));
unlink(tmpfile);
}
if (permanent)
unlink(pgstat_stat_filename);
/*
* Now throw away the list of requests. Note that requests sent after we
* started the write are still waiting on the network socket.
*/
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
list_free(pending_write_requests);
pending_write_requests = NIL;
}
/*
* return the filename for a DB stat file; filename is the output buffer,
* of length len.
*/
static void
get_dbstat_filename(bool permanent, bool tempname, Oid databaseid,
char *filename, int len)
{
int printed;
/* NB -- pgstat_reset_remove_files knows about the pattern this uses */
printed = snprintf(filename, len, "%s/db_%u.%s",
permanent ? PGSTAT_STAT_PERMANENT_DIRECTORY :
pgstat_stat_directory,
databaseid,
tempname ? "tmp" : "stat");
2018-08-15 22:29:31 +02:00
if (printed >= len)
elog(ERROR, "overlength pgstat path");
}
/* ----------
* pgstat_write_db_statsfile() -
* Write the stat file for a single database.
*
* If writing to the permanent file (happens when the collector is
* shutting down only), remove the temporary file so that backends
* starting up under a new postmaster can't read the old data before
* the new collector is ready.
* ----------
*/
static void
pgstat_write_db_statsfile(PgStat_StatDBEntry *dbentry, bool permanent)
{
HASH_SEQ_STATUS tstat;
HASH_SEQ_STATUS fstat;
PgStat_StatTabEntry *tabentry;
PgStat_StatFuncEntry *funcentry;
FILE *fpout;
int32 format_id;
Oid dbid = dbentry->databaseid;
int rc;
char tmpfile[MAXPGPATH];
char statfile[MAXPGPATH];
get_dbstat_filename(permanent, true, dbid, tmpfile, MAXPGPATH);
get_dbstat_filename(permanent, false, dbid, statfile, MAXPGPATH);
elog(DEBUG2, "writing stats file \"%s\"", statfile);
/*
* Open the statistics temp file to write out the current values.
*/
fpout = AllocateFile(tmpfile, PG_BINARY_W);
if (fpout == NULL)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not open temporary statistics file \"%s\": %m",
tmpfile)));
return;
}
/*
* Write the file header --- currently just a format ID.
*/
format_id = PGSTAT_FILE_FORMAT_ID;
rc = fwrite(&format_id, sizeof(format_id), 1, fpout);
(void) rc; /* we'll check for error with ferror */
/*
* Walk through the database's access stats per table.
*/
hash_seq_init(&tstat, dbentry->tables);
while ((tabentry = (PgStat_StatTabEntry *) hash_seq_search(&tstat)) != NULL)
{
fputc('T', fpout);
rc = fwrite(tabentry, sizeof(PgStat_StatTabEntry), 1, fpout);
(void) rc; /* we'll check for error with ferror */
}
/*
* Walk through the database's function stats table.
*/
hash_seq_init(&fstat, dbentry->functions);
while ((funcentry = (PgStat_StatFuncEntry *) hash_seq_search(&fstat)) != NULL)
{
fputc('F', fpout);
rc = fwrite(funcentry, sizeof(PgStat_StatFuncEntry), 1, fpout);
(void) rc; /* we'll check for error with ferror */
}
/*
* No more output to be done. Close the temp file and replace the old
* pgstat.stat with it. The ferror() check replaces testing for error
* after each individual fputc or fwrite above.
*/
fputc('E', fpout);
if (ferror(fpout))
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write temporary statistics file \"%s\": %m",
tmpfile)));
FreeFile(fpout);
unlink(tmpfile);
}
else if (FreeFile(fpout) < 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not close temporary statistics file \"%s\": %m",
tmpfile)));
unlink(tmpfile);
}
else if (rename(tmpfile, statfile) < 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not rename temporary statistics file \"%s\" to \"%s\": %m",
tmpfile, statfile)));
unlink(tmpfile);
}
if (permanent)
{
get_dbstat_filename(false, false, dbid, statfile, MAXPGPATH);
elog(DEBUG2, "removing temporary stats file \"%s\"", statfile);
unlink(statfile);
}
}
/* ----------
* pgstat_read_statsfiles() -
*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* Reads in some existing statistics collector files and returns the
* databases hash table that is the top level of the data.
*
* If 'onlydb' is not InvalidOid, it means we only want data for that DB
* plus the shared catalogs ("DB 0"). We'll still populate the DB hash
* table for all databases, but we don't bother even creating table/function
* hash tables for other databases.
*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* 'permanent' specifies reading from the permanent files not temporary ones.
* When true (happens only when the collector is starting up), remove the
* files after reading; the in-memory status is now authoritative, and the
* files would be out of date in case somebody else reads them.
*
* If a 'deep' read is requested, table/function stats are read, otherwise
* the table/function hash tables remain empty.
* ----------
*/
static HTAB *
pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep)
{
PgStat_StatDBEntry *dbentry;
PgStat_StatDBEntry dbbuf;
HASHCTL hash_ctl;
HTAB *dbhash;
FILE *fpin;
int32 format_id;
bool found;
const char *statfile = permanent ? PGSTAT_STAT_PERMANENT_FILENAME : pgstat_stat_filename;
/*
* The tables will live in pgStatLocalContext.
*/
pgstat_setup_memcxt();
/*
* Create the DB hashtable
*/
memset(&hash_ctl, 0, sizeof(hash_ctl));
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(PgStat_StatDBEntry);
hash_ctl.hcxt = pgStatLocalContext;
dbhash = hash_create("Databases hash", PGSTAT_DB_HASH_SIZE, &hash_ctl,
Improve hash_create's API for selecting simple-binary-key hash functions. Previously, if you wanted anything besides C-string hash keys, you had to specify a custom hashing function to hash_create(). Nearly all such callers were specifying tag_hash or oid_hash; which is tedious, and rather error-prone, since a caller could easily miss the opportunity to optimize by using hash_uint32 when appropriate. Replace this with a design whereby callers using simple binary-data keys just specify HASH_BLOBS and don't need to mess with specific support functions. hash_create() itself will take care of optimizing when the key size is four bytes. This nets out saving a few hundred bytes of code space, and offers a measurable performance improvement in tidbitmap.c (which was not exploiting the opportunity to use hash_uint32 for its 4-byte keys). There might be some wins elsewhere too, I didn't analyze closely. In future we could look into offering a similar optimized hashing function for 8-byte keys. Under this design that could be done in a centralized and machine-independent fashion, whereas getting it right for keys of platform-dependent sizes would've been notationally painful before. For the moment, the old way still works fine, so as not to break source code compatibility for loadable modules. Eventually we might want to remove tag_hash and friends from the exported API altogether, since there's no real need for them to be explicitly referenced from outside dynahash.c. Teodor Sigaev and Tom Lane
2014-12-18 19:36:29 +01:00
HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
/*
* Clear out global and archiver statistics so they start from zero in
* case we can't load an existing statsfile.
*/
memset(&globalStats, 0, sizeof(globalStats));
memset(&archiverStats, 0, sizeof(archiverStats));
/*
* Set the current timestamp (will be kept only in case we can't load an
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
* existing statsfile).
*/
globalStats.stat_reset_timestamp = GetCurrentTimestamp();
archiverStats.stat_reset_timestamp = globalStats.stat_reset_timestamp;
/*
* Try to open the stats file. If it doesn't exist, the backends simply
2005-10-15 04:49:52 +02:00
* return zero for anything and the collector simply starts from scratch
* with empty counters.
*
* ENOENT is a possibility if the stats collector is not running or has
* not yet written the stats file the first time. Any other failure
* condition is suspicious.
*/
if ((fpin = AllocateFile(statfile, PG_BINARY_R)) == NULL)
{
if (errno != ENOENT)
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errcode_for_file_access(),
errmsg("could not open statistics file \"%s\": %m",
statfile)));
return dbhash;
}
/*
* Verify it's of the expected format.
*/
if (fread(&format_id, 1, sizeof(format_id), fpin) != sizeof(format_id) ||
format_id != PGSTAT_FILE_FORMAT_ID)
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"", statfile)));
goto done;
}
/*
* Read global stats struct
*/
if (fread(&globalStats, 1, sizeof(globalStats), fpin) != sizeof(globalStats))
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"", statfile)));
Ignore old stats file timestamps when starting the stats collector. The stats collector disregards inquiry messages that bear a cutoff_time before when it last wrote the relevant stats file. That's fine, but at startup when it reads the "permanent" stats files, it absorbed their timestamps as if they were the times at which the corresponding temporary stats files had been written. In reality, of course, there's no data out there at all. This led to disregarding inquiry messages soon after startup if the postmaster had been shut down and restarted within less than PGSTAT_STAT_INTERVAL; which is a pretty common scenario, both for testing and in the field. Requesting backends would hang for 10 seconds and then report failure to read statistics, unless they got bailed out by some other backend coming along and making a newer request within that interval. I came across this through investigating unexpected delays in the src/test/recovery TAP tests: it manifests there because the autovacuum launcher hangs for 10 seconds when it can't get statistics at startup, thus preventing a second shutdown from occurring promptly. We might want to do some things in the autovac code to make it less prone to getting stuck that way, but this change is a good bug fix regardless. In passing, also fix pgstat_read_statsfiles() to ensure that it re-zeroes its global stats variables if they are corrupted by a short read from the stats file. (Other reads in that function go into temp variables, so that the issue doesn't arise.) This has been broken since we created the separation between permanent and temporary stats files in 8.4, so back-patch to all supported branches. Discussion: https://postgr.es/m/16860.1498442626@sss.pgh.pa.us
2017-06-26 22:17:05 +02:00
memset(&globalStats, 0, sizeof(globalStats));
goto done;
}
Ignore old stats file timestamps when starting the stats collector. The stats collector disregards inquiry messages that bear a cutoff_time before when it last wrote the relevant stats file. That's fine, but at startup when it reads the "permanent" stats files, it absorbed their timestamps as if they were the times at which the corresponding temporary stats files had been written. In reality, of course, there's no data out there at all. This led to disregarding inquiry messages soon after startup if the postmaster had been shut down and restarted within less than PGSTAT_STAT_INTERVAL; which is a pretty common scenario, both for testing and in the field. Requesting backends would hang for 10 seconds and then report failure to read statistics, unless they got bailed out by some other backend coming along and making a newer request within that interval. I came across this through investigating unexpected delays in the src/test/recovery TAP tests: it manifests there because the autovacuum launcher hangs for 10 seconds when it can't get statistics at startup, thus preventing a second shutdown from occurring promptly. We might want to do some things in the autovac code to make it less prone to getting stuck that way, but this change is a good bug fix regardless. In passing, also fix pgstat_read_statsfiles() to ensure that it re-zeroes its global stats variables if they are corrupted by a short read from the stats file. (Other reads in that function go into temp variables, so that the issue doesn't arise.) This has been broken since we created the separation between permanent and temporary stats files in 8.4, so back-patch to all supported branches. Discussion: https://postgr.es/m/16860.1498442626@sss.pgh.pa.us
2017-06-26 22:17:05 +02:00
/*
* In the collector, disregard the timestamp we read from the permanent
* stats file; we should be willing to write a temp stats file immediately
* upon the first request from any backend. This only matters if the old
* file's timestamp is less than PGSTAT_STAT_INTERVAL ago, but that's not
* an unusual scenario.
*/
if (pgStatRunningInCollector)
globalStats.stats_timestamp = 0;
/*
* Read archiver stats struct
*/
if (fread(&archiverStats, 1, sizeof(archiverStats), fpin) != sizeof(archiverStats))
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"", statfile)));
Ignore old stats file timestamps when starting the stats collector. The stats collector disregards inquiry messages that bear a cutoff_time before when it last wrote the relevant stats file. That's fine, but at startup when it reads the "permanent" stats files, it absorbed their timestamps as if they were the times at which the corresponding temporary stats files had been written. In reality, of course, there's no data out there at all. This led to disregarding inquiry messages soon after startup if the postmaster had been shut down and restarted within less than PGSTAT_STAT_INTERVAL; which is a pretty common scenario, both for testing and in the field. Requesting backends would hang for 10 seconds and then report failure to read statistics, unless they got bailed out by some other backend coming along and making a newer request within that interval. I came across this through investigating unexpected delays in the src/test/recovery TAP tests: it manifests there because the autovacuum launcher hangs for 10 seconds when it can't get statistics at startup, thus preventing a second shutdown from occurring promptly. We might want to do some things in the autovac code to make it less prone to getting stuck that way, but this change is a good bug fix regardless. In passing, also fix pgstat_read_statsfiles() to ensure that it re-zeroes its global stats variables if they are corrupted by a short read from the stats file. (Other reads in that function go into temp variables, so that the issue doesn't arise.) This has been broken since we created the separation between permanent and temporary stats files in 8.4, so back-patch to all supported branches. Discussion: https://postgr.es/m/16860.1498442626@sss.pgh.pa.us
2017-06-26 22:17:05 +02:00
memset(&archiverStats, 0, sizeof(archiverStats));
goto done;
}
/*
* We found an existing collector stats file. Read it and put all the
* hashtable entries into place.
*/
for (;;)
{
switch (fgetc(fpin))
{
/*
* 'D' A PgStat_StatDBEntry struct describing a database
* follows.
*/
case 'D':
if (fread(&dbbuf, 1, offsetof(PgStat_StatDBEntry, tables),
fpin) != offsetof(PgStat_StatDBEntry, tables))
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"",
statfile)));
goto done;
}
/*
* Add to the DB hash
*/
dbentry = (PgStat_StatDBEntry *) hash_search(dbhash,
(void *) &dbbuf.databaseid,
HASH_ENTER,
&found);
if (found)
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"",
statfile)));
goto done;
}
memcpy(dbentry, &dbbuf, sizeof(PgStat_StatDBEntry));
dbentry->tables = NULL;
dbentry->functions = NULL;
Ignore old stats file timestamps when starting the stats collector. The stats collector disregards inquiry messages that bear a cutoff_time before when it last wrote the relevant stats file. That's fine, but at startup when it reads the "permanent" stats files, it absorbed their timestamps as if they were the times at which the corresponding temporary stats files had been written. In reality, of course, there's no data out there at all. This led to disregarding inquiry messages soon after startup if the postmaster had been shut down and restarted within less than PGSTAT_STAT_INTERVAL; which is a pretty common scenario, both for testing and in the field. Requesting backends would hang for 10 seconds and then report failure to read statistics, unless they got bailed out by some other backend coming along and making a newer request within that interval. I came across this through investigating unexpected delays in the src/test/recovery TAP tests: it manifests there because the autovacuum launcher hangs for 10 seconds when it can't get statistics at startup, thus preventing a second shutdown from occurring promptly. We might want to do some things in the autovac code to make it less prone to getting stuck that way, but this change is a good bug fix regardless. In passing, also fix pgstat_read_statsfiles() to ensure that it re-zeroes its global stats variables if they are corrupted by a short read from the stats file. (Other reads in that function go into temp variables, so that the issue doesn't arise.) This has been broken since we created the separation between permanent and temporary stats files in 8.4, so back-patch to all supported branches. Discussion: https://postgr.es/m/16860.1498442626@sss.pgh.pa.us
2017-06-26 22:17:05 +02:00
/*
* In the collector, disregard the timestamp we read from the
* permanent stats file; we should be willing to write a temp
* stats file immediately upon the first request from any
* backend.
*/
if (pgStatRunningInCollector)
dbentry->stats_timestamp = 0;
/*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* Don't create tables/functions hashtables for uninteresting
* databases.
*/
if (onlydb != InvalidOid)
{
if (dbbuf.databaseid != onlydb &&
dbbuf.databaseid != InvalidOid)
2005-10-15 04:49:52 +02:00
break;
}
memset(&hash_ctl, 0, sizeof(hash_ctl));
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(PgStat_StatTabEntry);
hash_ctl.hcxt = pgStatLocalContext;
dbentry->tables = hash_create("Per-database table",
PGSTAT_TAB_HASH_SIZE,
&hash_ctl,
HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(PgStat_StatFuncEntry);
hash_ctl.hcxt = pgStatLocalContext;
dbentry->functions = hash_create("Per-database function",
PGSTAT_FUNCTION_HASH_SIZE,
&hash_ctl,
HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
/*
* If requested, read the data from the database-specific
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* file. Otherwise we just leave the hashtables empty.
*/
if (deep)
pgstat_read_db_statsfile(dbentry->databaseid,
dbentry->tables,
dbentry->functions,
permanent);
break;
case 'E':
goto done;
default:
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"",
statfile)));
goto done;
}
}
done:
FreeFile(fpin);
/* If requested to read the permanent file, also get rid of it. */
if (permanent)
{
elog(DEBUG2, "removing permanent stats file \"%s\"", statfile);
unlink(statfile);
}
return dbhash;
}
/* ----------
* pgstat_read_db_statsfile() -
*
* Reads in the existing statistics collector file for the given database,
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* filling the passed-in tables and functions hash tables.
*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* As in pgstat_read_statsfiles, if the permanent file is requested, it is
* removed after reading.
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
*
* Note: this code has the ability to skip storing per-table or per-function
* data, if NULL is passed for the corresponding hashtable. That's not used
* at the moment though.
* ----------
*/
static void
pgstat_read_db_statsfile(Oid databaseid, HTAB *tabhash, HTAB *funchash,
bool permanent)
{
PgStat_StatTabEntry *tabentry;
PgStat_StatTabEntry tabbuf;
PgStat_StatFuncEntry funcbuf;
PgStat_StatFuncEntry *funcentry;
FILE *fpin;
int32 format_id;
bool found;
char statfile[MAXPGPATH];
get_dbstat_filename(permanent, false, databaseid, statfile, MAXPGPATH);
/*
* Try to open the stats file. If it doesn't exist, the backends simply
* return zero for anything and the collector simply starts from scratch
* with empty counters.
*
* ENOENT is a possibility if the stats collector is not running or has
* not yet written the stats file the first time. Any other failure
* condition is suspicious.
*/
if ((fpin = AllocateFile(statfile, PG_BINARY_R)) == NULL)
{
if (errno != ENOENT)
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errcode_for_file_access(),
errmsg("could not open statistics file \"%s\": %m",
statfile)));
return;
}
/*
* Verify it's of the expected format.
*/
if (fread(&format_id, 1, sizeof(format_id), fpin) != sizeof(format_id) ||
format_id != PGSTAT_FILE_FORMAT_ID)
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"", statfile)));
goto done;
}
/*
* We found an existing collector stats file. Read it and put all the
* hashtable entries into place.
*/
for (;;)
{
switch (fgetc(fpin))
{
/*
* 'T' A PgStat_StatTabEntry follows.
*/
case 'T':
if (fread(&tabbuf, 1, sizeof(PgStat_StatTabEntry),
fpin) != sizeof(PgStat_StatTabEntry))
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"",
statfile)));
goto done;
}
/*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* Skip if table data not wanted.
*/
if (tabhash == NULL)
break;
tabentry = (PgStat_StatTabEntry *) hash_search(tabhash,
(void *) &tabbuf.tableid,
HASH_ENTER, &found);
if (found)
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"",
statfile)));
goto done;
}
memcpy(tabentry, &tabbuf, sizeof(tabbuf));
break;
/*
* 'F' A PgStat_StatFuncEntry follows.
*/
case 'F':
if (fread(&funcbuf, 1, sizeof(PgStat_StatFuncEntry),
fpin) != sizeof(PgStat_StatFuncEntry))
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"",
statfile)));
goto done;
}
/*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* Skip if function data not wanted.
*/
if (funchash == NULL)
break;
funcentry = (PgStat_StatFuncEntry *) hash_search(funchash,
(void *) &funcbuf.functionid,
HASH_ENTER, &found);
if (found)
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"",
statfile)));
goto done;
}
memcpy(funcentry, &funcbuf, sizeof(funcbuf));
break;
/*
* 'E' The EOF marker of a complete stats file.
*/
case 'E':
goto done;
default:
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"",
statfile)));
goto done;
}
}
done:
FreeFile(fpin);
if (permanent)
{
elog(DEBUG2, "removing permanent stats file \"%s\"", statfile);
unlink(statfile);
}
}
/* ----------
* pgstat_read_db_statsfile_timestamp() -
*
* Attempt to determine the timestamp of the last db statfile write.
* Returns true if successful; the timestamp is stored in *ts.
*
* This needs to be careful about handling databases for which no stats file
* exists, such as databases without a stat entry or those not yet written:
*
* - if there's a database entry in the global file, return the corresponding
* stats_timestamp value.
*
* - if there's no db stat entry (e.g. for a new or inactive database),
* there's no stats_timestamp value, but also nothing to write so we return
* the timestamp of the global statfile.
* ----------
*/
static bool
pgstat_read_db_statsfile_timestamp(Oid databaseid, bool permanent,
TimestampTz *ts)
{
PgStat_StatDBEntry dbentry;
PgStat_GlobalStats myGlobalStats;
PgStat_ArchiverStats myArchiverStats;
FILE *fpin;
int32 format_id;
const char *statfile = permanent ? PGSTAT_STAT_PERMANENT_FILENAME : pgstat_stat_filename;
/*
* Try to open the stats file. As above, anything but ENOENT is worthy of
* complaining about.
*/
if ((fpin = AllocateFile(statfile, PG_BINARY_R)) == NULL)
{
if (errno != ENOENT)
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errcode_for_file_access(),
errmsg("could not open statistics file \"%s\": %m",
statfile)));
return false;
}
/*
* Verify it's of the expected format.
*/
if (fread(&format_id, 1, sizeof(format_id), fpin) != sizeof(format_id) ||
format_id != PGSTAT_FILE_FORMAT_ID)
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"", statfile)));
FreeFile(fpin);
return false;
}
/*
* Read global stats struct
*/
if (fread(&myGlobalStats, 1, sizeof(myGlobalStats),
fpin) != sizeof(myGlobalStats))
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"", statfile)));
FreeFile(fpin);
return false;
}
/*
* Read archiver stats struct
*/
if (fread(&myArchiverStats, 1, sizeof(myArchiverStats),
fpin) != sizeof(myArchiverStats))
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"", statfile)));
FreeFile(fpin);
return false;
}
/* By default, we're going to return the timestamp of the global file. */
*ts = myGlobalStats.stats_timestamp;
/*
* We found an existing collector stats file. Read it and look for a
* record for the requested database. If found, use its timestamp.
*/
for (;;)
{
switch (fgetc(fpin))
{
/*
* 'D' A PgStat_StatDBEntry struct describing a database
* follows.
*/
case 'D':
if (fread(&dbentry, 1, offsetof(PgStat_StatDBEntry, tables),
fpin) != offsetof(PgStat_StatDBEntry, tables))
{
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"",
statfile)));
goto done;
}
/*
* If this is the DB we're looking for, save its timestamp and
* we're done.
*/
if (dbentry.databaseid == databaseid)
{
*ts = dbentry.stats_timestamp;
goto done;
}
break;
case 'E':
goto done;
default:
ereport(pgStatRunningInCollector ? LOG : WARNING,
(errmsg("corrupted statistics file \"%s\"",
statfile)));
goto done;
}
}
done:
FreeFile(fpin);
return true;
}
/*
* If not already done, read the statistics collector stats file into
* some hash tables. The results will be kept until pgstat_clear_snapshot()
* is called (typically, at end of transaction).
*/
static void
backend_read_statsfile(void)
{
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
TimestampTz min_ts = 0;
TimestampTz ref_ts = 0;
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
Oid inquiry_db;
int count;
/* already read it? */
if (pgStatDBHash)
return;
Assert(!pgStatRunningInCollector);
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
/*
* In a normal backend, we check staleness of the data for our own DB, and
* so we send MyDatabaseId in inquiry messages. In the autovac launcher,
* check staleness of the shared-catalog data, and send InvalidOid in
* inquiry messages so as not to force writing unnecessary data.
*/
if (IsAutoVacuumLauncherProcess())
inquiry_db = InvalidOid;
else
inquiry_db = MyDatabaseId;
/*
* Loop until fresh enough stats file is available or we ran out of time.
* The stats inquiry message is sent repeatedly in case collector drops
* it; but not every single time, as that just swamps the collector.
*/
for (count = 0; count < PGSTAT_POLL_LOOP_COUNT; count++)
{
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
bool ok;
TimestampTz file_ts = 0;
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
TimestampTz cur_ts;
CHECK_FOR_INTERRUPTS();
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
ok = pgstat_read_db_statsfile_timestamp(inquiry_db, false, &file_ts);
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
cur_ts = GetCurrentTimestamp();
/* Calculate min acceptable timestamp, if we didn't already */
if (count == 0 || cur_ts < ref_ts)
{
/*
* We set the minimum acceptable timestamp to PGSTAT_STAT_INTERVAL
* msec before now. This indirectly ensures that the collector
* needn't write the file more often than PGSTAT_STAT_INTERVAL. In
* an autovacuum worker, however, we want a lower delay to avoid
* using stale data, so we use PGSTAT_RETRY_DELAY (since the
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
* number of workers is low, this shouldn't be a problem).
*
* We don't recompute min_ts after sleeping, except in the
* unlikely case that cur_ts went backwards. So we might end up
* accepting a file a bit older than PGSTAT_STAT_INTERVAL. In
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
* practice that shouldn't happen, though, as long as the sleep
* time is less than PGSTAT_STAT_INTERVAL; and we don't want to
* tell the collector that our cutoff time is less than what we'd
* actually accept.
*/
ref_ts = cur_ts;
if (IsAutoVacuumWorkerProcess())
min_ts = TimestampTzPlusMilliseconds(ref_ts,
-PGSTAT_RETRY_DELAY);
else
min_ts = TimestampTzPlusMilliseconds(ref_ts,
-PGSTAT_STAT_INTERVAL);
}
/*
* If the file timestamp is actually newer than cur_ts, we must have
* had a clock glitch (system time went backwards) or there is clock
* skew between our processor and the stats collector's processor.
* Accept the file, but send an inquiry message anyway to make
* pgstat_recv_inquiry do a sanity check on the collector's time.
*/
if (ok && file_ts > cur_ts)
{
/*
* A small amount of clock skew between processors isn't terribly
* surprising, but a large difference is worth logging. We
* arbitrarily define "large" as 1000 msec.
*/
if (file_ts >= TimestampTzPlusMilliseconds(cur_ts, 1000))
{
char *filetime;
char *mytime;
/* Copy because timestamptz_to_str returns a static buffer */
filetime = pstrdup(timestamptz_to_str(file_ts));
mytime = pstrdup(timestamptz_to_str(cur_ts));
elog(LOG, "stats collector's time %s is later than backend local time %s",
filetime, mytime);
pfree(filetime);
pfree(mytime);
}
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
pgstat_send_inquiry(cur_ts, min_ts, inquiry_db);
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
break;
}
/* Normal acceptance case: file is not older than cutoff time */
if (ok && file_ts >= min_ts)
break;
/* Not there or too old, so kick the collector and wait a bit */
if ((count % PGSTAT_INQ_LOOP_COUNT) == 0)
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
pgstat_send_inquiry(cur_ts, min_ts, inquiry_db);
pg_usleep(PGSTAT_RETRY_DELAY * 1000L);
}
if (count >= PGSTAT_POLL_LOOP_COUNT)
ereport(LOG,
(errmsg("using stale statistics instead of current ones "
"because stats collector is not responding")));
/*
* Autovacuum launcher wants stats about all databases, but a shallow read
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* is sufficient. Regular backends want a deep read for just the tables
* they can see (MyDatabaseId + shared catalogs).
*/
if (IsAutoVacuumLauncherProcess())
pgStatDBHash = pgstat_read_statsfiles(InvalidOid, false, false);
else
pgStatDBHash = pgstat_read_statsfiles(MyDatabaseId, false, true);
}
/* ----------
* pgstat_setup_memcxt() -
*
* Create pgStatLocalContext, if not already done.
* ----------
*/
static void
pgstat_setup_memcxt(void)
{
if (!pgStatLocalContext)
pgStatLocalContext = AllocSetContextCreate(TopMemoryContext,
"Statistics snapshot",
Add macros to make AllocSetContextCreate() calls simpler and safer. I found that half a dozen (nearly 5%) of our AllocSetContextCreate calls had typos in the context-sizing parameters. While none of these led to especially significant problems, they did create minor inefficiencies, and it's now clear that expecting people to copy-and-paste those calls accurately is not a great idea. Let's reduce the risk of future errors by introducing single macros that encapsulate the common use-cases. Three such macros are enough to cover all but two special-purpose contexts; those two calls can be left as-is, I think. While this patch doesn't in itself improve matters for third-party extensions, it doesn't break anything for them either, and they can gradually adopt the simplified notation over time. In passing, change TopMemoryContext to use the default allocation parameters. Formerly it could only be extended 8K at a time. That was probably reasonable when this code was written; but nowadays we create many more contexts than we did then, so that it's not unusual to have a couple hundred K in TopMemoryContext, even without considering various dubious code that sticks other things there. There seems no good reason not to let it use growing blocks like most other contexts. Back-patch to 9.6, mostly because that's still close enough to HEAD that it's easy to do so, and keeping the branches in sync can be expected to avoid some future back-patching pain. The bugs fixed by these changes don't seem to be significant enough to justify fixing them further back. Discussion: <21072.1472321324@sss.pgh.pa.us>
2016-08-27 23:50:38 +02:00
ALLOCSET_SMALL_SIZES);
}
/* ----------
* pgstat_clear_snapshot() -
*
* Discard any data collected in the current transaction. Any subsequent
* request will cause new snapshots to be read.
*
* This is also invoked during transaction commit or abort to discard
* the no-longer-wanted snapshot.
* ----------
*/
void
pgstat_clear_snapshot(void)
{
/* Release memory, if any was allocated */
if (pgStatLocalContext)
MemoryContextDelete(pgStatLocalContext);
/* Reset variables */
pgStatLocalContext = NULL;
pgStatDBHash = NULL;
localBackendStatusTable = NULL;
localNumBackends = 0;
}
/* ----------
* pgstat_recv_inquiry() -
*
* Process stat inquiry requests.
* ----------
*/
static void
pgstat_recv_inquiry(PgStat_MsgInquiry *msg, int len)
{
PgStat_StatDBEntry *dbentry;
elog(DEBUG2, "received inquiry for database %u", msg->databaseid);
/*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* If there's already a write request for this DB, there's nothing to do.
2013-02-21 15:46:46 +01:00
*
* Note that if a request is found, we return early and skip the below
* check for clock skew. This is okay, since the only way for a DB
* request to be present in the list is that we have been here since the
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* last write round. It seems sufficient to check for clock skew once per
* write round.
*/
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
if (list_member_oid(pending_write_requests, msg->databaseid))
return;
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
/*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* Check to see if we last wrote this database at a time >= the requested
* cutoff time. If so, this is a stale request that was generated before
* we updated the DB file, and we don't need to do so again.
*
* If the requestor's local clock time is older than stats_timestamp, we
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
* should suspect a clock glitch, ie system time going backwards; though
* the more likely explanation is just delayed message receipt. It is
* worth expending a GetCurrentTimestamp call to be sure, since a large
* retreat in the system clock reading could otherwise cause us to neglect
* to update the stats file for a long time.
*/
dbentry = pgstat_get_db_entry(msg->databaseid, false);
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
if (dbentry == NULL)
{
/*
* We have no data for this DB. Enter a write request anyway so that
* the global stats will get updated. This is needed to prevent
* backend_read_statsfile from waiting for data that we cannot supply,
* in the case of a new DB that nobody has yet reported any stats for.
* See the behavior of pgstat_read_db_statsfile_timestamp.
*/
}
else if (msg->clock_time < dbentry->stats_timestamp)
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
{
TimestampTz cur_ts = GetCurrentTimestamp();
if (cur_ts < dbentry->stats_timestamp)
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
{
/*
* Sure enough, time went backwards. Force a new stats file write
* to get back in sync; but first, log a complaint.
*/
char *writetime;
char *mytime;
/* Copy because timestamptz_to_str returns a static buffer */
writetime = pstrdup(timestamptz_to_str(dbentry->stats_timestamp));
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
mytime = pstrdup(timestamptz_to_str(cur_ts));
elog(LOG,
"stats_timestamp %s is later than collector's time %s for database %u",
writetime, mytime, dbentry->databaseid);
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
pfree(writetime);
pfree(mytime);
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
}
else
{
/*
* Nope, it's just an old request. Assuming msg's clock_time is
* >= its cutoff_time, it must be stale, so we can ignore it.
*/
return;
Fix stats collector to recover nicely when system clock goes backwards. Formerly, if the system clock went backwards, the stats collector would fail to update the stats file any more until the clock reading again exceeds whatever timestamp was last written into the stats file. Such glitches in the clock's behavior are not terribly unlikely on machines not using NTP. Such a scenario has been observed to cause regression test failures in the buildfarm, and it could have bad effects on the behavior of autovacuum, so it seems prudent to install some defenses. We could directly detect the clock going backwards by adding GetCurrentTimestamp calls in the stats collector's main loop, but that would hurt performance on platforms where GetCurrentTimestamp is expensive. To minimize the performance hit in normal cases, adopt a more complicated scheme wherein backends check for clock skew when reading the stats file, and if they see it, signal the stats collector by sending an extra stats inquiry message. The stats collector does an extra GetCurrentTimestamp only when it receives an inquiry with an apparently out-of-order timestamp. To avoid unnecessary GetCurrentTimestamp calls, expand the inquiry messages to carry the backend's current clock reading as well as its stats cutoff time. The latter, being intentionally slightly in-the-past, would trigger more clock rechecks than we need if it were used for this purpose. We might want to backpatch this change at some point, but let's let it shake out in the buildfarm for awhile first.
2012-06-17 23:11:07 +02:00
}
}
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
else if (msg->cutoff_time <= dbentry->stats_timestamp)
{
/* Stale request, ignore it */
return;
}
/*
* We need to write this DB, so create a request.
*/
pending_write_requests = lappend_oid(pending_write_requests,
msg->databaseid);
}
/* ----------
* pgstat_recv_tabstat() -
*
* Count what the backend has done.
* ----------
*/
static void
pgstat_recv_tabstat(PgStat_MsgTabstat *msg, int len)
{
PgStat_StatDBEntry *dbentry;
PgStat_StatTabEntry *tabentry;
int i;
bool found;
dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
/*
* Update database-wide stats.
*/
dbentry->n_xact_commit += (PgStat_Counter) (msg->m_xact_commit);
dbentry->n_xact_rollback += (PgStat_Counter) (msg->m_xact_rollback);
dbentry->n_block_read_time += msg->m_block_read_time;
dbentry->n_block_write_time += msg->m_block_write_time;
/*
* Process all table entries in the message.
*/
for (i = 0; i < msg->m_nentries; i++)
{
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
PgStat_TableEntry *tabmsg = &(msg->m_entry[i]);
tabentry = (PgStat_StatTabEntry *) hash_search(dbentry->tables,
(void *) &(tabmsg->t_id),
2005-10-15 04:49:52 +02:00
HASH_ENTER, &found);
if (!found)
{
/*
2005-10-15 04:49:52 +02:00
* If it's a new table entry, initialize counters to the values we
* just got.
*/
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
tabentry->numscans = tabmsg->t_counts.t_numscans;
tabentry->tuples_returned = tabmsg->t_counts.t_tuples_returned;
tabentry->tuples_fetched = tabmsg->t_counts.t_tuples_fetched;
tabentry->tuples_inserted = tabmsg->t_counts.t_tuples_inserted;
tabentry->tuples_updated = tabmsg->t_counts.t_tuples_updated;
tabentry->tuples_deleted = tabmsg->t_counts.t_tuples_deleted;
tabentry->tuples_hot_updated = tabmsg->t_counts.t_tuples_hot_updated;
tabentry->n_live_tuples = tabmsg->t_counts.t_delta_live_tuples;
tabentry->n_dead_tuples = tabmsg->t_counts.t_delta_dead_tuples;
tabentry->changes_since_analyze = tabmsg->t_counts.t_changed_tuples;
tabentry->blocks_fetched = tabmsg->t_counts.t_blocks_fetched;
tabentry->blocks_hit = tabmsg->t_counts.t_blocks_hit;
tabentry->vacuum_timestamp = 0;
tabentry->vacuum_count = 0;
tabentry->autovac_vacuum_timestamp = 0;
tabentry->autovac_vacuum_count = 0;
tabentry->analyze_timestamp = 0;
tabentry->analyze_count = 0;
tabentry->autovac_analyze_timestamp = 0;
tabentry->autovac_analyze_count = 0;
}
else
{
/*
* Otherwise add the values to the existing entry.
*/
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
tabentry->numscans += tabmsg->t_counts.t_numscans;
tabentry->tuples_returned += tabmsg->t_counts.t_tuples_returned;
tabentry->tuples_fetched += tabmsg->t_counts.t_tuples_fetched;
tabentry->tuples_inserted += tabmsg->t_counts.t_tuples_inserted;
tabentry->tuples_updated += tabmsg->t_counts.t_tuples_updated;
tabentry->tuples_deleted += tabmsg->t_counts.t_tuples_deleted;
tabentry->tuples_hot_updated += tabmsg->t_counts.t_tuples_hot_updated;
/* If table was truncated, first reset the live/dead counters */
if (tabmsg->t_counts.t_truncated)
{
tabentry->n_live_tuples = 0;
tabentry->n_dead_tuples = 0;
}
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
tabentry->n_live_tuples += tabmsg->t_counts.t_delta_live_tuples;
tabentry->n_dead_tuples += tabmsg->t_counts.t_delta_dead_tuples;
tabentry->changes_since_analyze += tabmsg->t_counts.t_changed_tuples;
tabentry->blocks_fetched += tabmsg->t_counts.t_blocks_fetched;
tabentry->blocks_hit += tabmsg->t_counts.t_blocks_hit;
}
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/* Clamp n_live_tuples in case of negative delta_live_tuples */
tabentry->n_live_tuples = Max(tabentry->n_live_tuples, 0);
/* Likewise for n_dead_tuples */
tabentry->n_dead_tuples = Max(tabentry->n_dead_tuples, 0);
/*
* Add per-table stats to the per-database entry, too.
*/
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
dbentry->n_tuples_returned += tabmsg->t_counts.t_tuples_returned;
dbentry->n_tuples_fetched += tabmsg->t_counts.t_tuples_fetched;
dbentry->n_tuples_inserted += tabmsg->t_counts.t_tuples_inserted;
dbentry->n_tuples_updated += tabmsg->t_counts.t_tuples_updated;
dbentry->n_tuples_deleted += tabmsg->t_counts.t_tuples_deleted;
dbentry->n_blocks_fetched += tabmsg->t_counts.t_blocks_fetched;
dbentry->n_blocks_hit += tabmsg->t_counts.t_blocks_hit;
}
}
/* ----------
* pgstat_recv_tabpurge() -
*
* Arrange for dead table removal.
* ----------
*/
static void
pgstat_recv_tabpurge(PgStat_MsgTabpurge *msg, int len)
{
PgStat_StatDBEntry *dbentry;
int i;
dbentry = pgstat_get_db_entry(msg->m_databaseid, false);
/*
* No need to purge if we don't even know the database.
*/
if (!dbentry || !dbentry->tables)
return;
/*
* Process all table entries in the message.
*/
for (i = 0; i < msg->m_nentries; i++)
{
/* Remove from hashtable if present; we don't care if it's not. */
(void) hash_search(dbentry->tables,
(void *) &(msg->m_tableid[i]),
HASH_REMOVE, NULL);
}
}
/* ----------
* pgstat_recv_dropdb() -
*
* Arrange for dead database removal
* ----------
*/
static void
pgstat_recv_dropdb(PgStat_MsgDropdb *msg, int len)
{
Oid dbid = msg->m_databaseid;
PgStat_StatDBEntry *dbentry;
/*
* Lookup the database in the hashtable.
*/
dbentry = pgstat_get_db_entry(dbid, false);
/*
* If found, remove it (along with the db statfile).
*/
if (dbentry)
{
char statfile[MAXPGPATH];
get_dbstat_filename(false, false, dbid, statfile, MAXPGPATH);
elog(DEBUG2, "removing stats file \"%s\"", statfile);
unlink(statfile);
if (dbentry->tables != NULL)
hash_destroy(dbentry->tables);
if (dbentry->functions != NULL)
hash_destroy(dbentry->functions);
if (hash_search(pgStatDBHash,
(void *) &dbid,
HASH_REMOVE, NULL) == NULL)
ereport(ERROR,
(errmsg("database hash table corrupted during cleanup --- abort")));
}
}
/* ----------
* pgstat_recv_resetcounter() -
*
* Reset the statistics for the specified database.
* ----------
*/
static void
pgstat_recv_resetcounter(PgStat_MsgResetcounter *msg, int len)
{
PgStat_StatDBEntry *dbentry;
/*
* Lookup the database in the hashtable. Nothing to do if not there.
*/
dbentry = pgstat_get_db_entry(msg->m_databaseid, false);
if (!dbentry)
return;
/*
2005-10-15 04:49:52 +02:00
* We simply throw away all the database's table entries by recreating a
* new hash table for them.
*/
if (dbentry->tables != NULL)
hash_destroy(dbentry->tables);
if (dbentry->functions != NULL)
hash_destroy(dbentry->functions);
dbentry->tables = NULL;
dbentry->functions = NULL;
/*
* Reset database-level stats, too. This creates empty hash tables for
* tables and functions.
*/
reset_dbentry_counters(dbentry);
}
/* ----------
* pgstat_recv_resetshared() -
*
* Reset some shared statistics of the cluster.
* ----------
*/
static void
pgstat_recv_resetsharedcounter(PgStat_MsgResetsharedcounter *msg, int len)
{
2010-02-26 03:01:40 +01:00
if (msg->m_resettarget == RESET_BGWRITER)
{
/* Reset the global background writer statistics for the cluster. */
memset(&globalStats, 0, sizeof(globalStats));
globalStats.stat_reset_timestamp = GetCurrentTimestamp();
}
else if (msg->m_resettarget == RESET_ARCHIVER)
{
/* Reset the archiver statistics for the cluster. */
memset(&archiverStats, 0, sizeof(archiverStats));
archiverStats.stat_reset_timestamp = GetCurrentTimestamp();
}
/*
* Presumably the sender of this message validated the target, don't
* complain here if it's not valid
*/
}
/* ----------
* pgstat_recv_resetsinglecounter() -
*
* Reset a statistics for a single object
* ----------
*/
static void
pgstat_recv_resetsinglecounter(PgStat_MsgResetsinglecounter *msg, int len)
{
PgStat_StatDBEntry *dbentry;
dbentry = pgstat_get_db_entry(msg->m_databaseid, false);
if (!dbentry)
return;
/* Set the reset timestamp for the whole database */
dbentry->stat_reset_timestamp = GetCurrentTimestamp();
/* Remove object if it exists, ignore it if not */
if (msg->m_resettype == RESET_TABLE)
(void) hash_search(dbentry->tables, (void *) &(msg->m_objectid),
HASH_REMOVE, NULL);
else if (msg->m_resettype == RESET_FUNCTION)
(void) hash_search(dbentry->functions, (void *) &(msg->m_objectid),
HASH_REMOVE, NULL);
}
/* ----------
* pgstat_recv_autovac() -
*
* Process an autovacuum signalling message.
* ----------
*/
static void
pgstat_recv_autovac(PgStat_MsgAutovacStart *msg, int len)
{
PgStat_StatDBEntry *dbentry;
/*
* Store the last autovacuum time in the database's hashtable entry.
*/
dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
dbentry->last_autovac_time = msg->m_start_time;
}
/* ----------
* pgstat_recv_vacuum() -
*
* Process a VACUUM message.
* ----------
*/
static void
pgstat_recv_vacuum(PgStat_MsgVacuum *msg, int len)
{
PgStat_StatDBEntry *dbentry;
PgStat_StatTabEntry *tabentry;
/*
* Store the data in the table's hashtable entry.
*/
dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
tabentry = pgstat_get_tab_entry(dbentry, msg->m_tableoid, true);
tabentry->n_live_tuples = msg->m_live_tuples;
tabentry->n_dead_tuples = msg->m_dead_tuples;
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
if (msg->m_autovacuum)
{
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
tabentry->autovac_vacuum_timestamp = msg->m_vacuumtime;
tabentry->autovac_vacuum_count++;
}
else
{
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
tabentry->vacuum_timestamp = msg->m_vacuumtime;
tabentry->vacuum_count++;
}
}
/* ----------
* pgstat_recv_analyze() -
*
* Process an ANALYZE message.
* ----------
*/
static void
pgstat_recv_analyze(PgStat_MsgAnalyze *msg, int len)
{
PgStat_StatDBEntry *dbentry;
PgStat_StatTabEntry *tabentry;
/*
* Store the data in the table's hashtable entry.
*/
dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
tabentry = pgstat_get_tab_entry(dbentry, msg->m_tableoid, true);
Fix VACUUM so that it always updates pg_class.reltuples/relpages. When we added the ability for vacuum to skip heap pages by consulting the visibility map, we made it just not update the reltuples/relpages statistics if it skipped any pages. But this could leave us with extremely out-of-date stats for a table that contains any unchanging areas, especially for TOAST tables which never get processed by ANALYZE. In particular this could result in autovacuum making poor decisions about when to process the table, as in recent report from Florian Helmberger. And in general it's a bad idea to not update the stats at all. Instead, use the previous values of reltuples/relpages as an estimate of the tuple density in unvisited pages. This approach results in a "moving average" estimate of reltuples, which should converge to the correct value over multiple VACUUM and ANALYZE cycles even when individual measurements aren't very good. This new method for updating reltuples is used by both VACUUM and ANALYZE, with the result that we no longer need the grotty interconnections that caused ANALYZE to not update the stats depending on what had happened in the parent VACUUM command. Also, fix the logic for skipping all-visible pages during VACUUM so that it looks ahead rather than behind to decide what to do, as per a suggestion from Greg Stark. This eliminates useless scanning of all-visible pages at the start of the relation or just after a not-all-visible page. In particular, the first few pages of the relation will not be invariably included in the scanned pages, which seems to help in not overweighting them in the reltuples estimate. Back-patch to 8.4, where the visibility map was introduced.
2011-05-30 23:05:26 +02:00
tabentry->n_live_tuples = msg->m_live_tuples;
tabentry->n_dead_tuples = msg->m_dead_tuples;
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
/*
* If commanded, reset changes_since_analyze to zero. This forgets any
* changes that were committed while the ANALYZE was in progress, but we
* have no good way to estimate how many of those there were.
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
*/
if (msg->m_resetcounter)
tabentry->changes_since_analyze = 0;
Revise pgstat's tracking of tuple changes to improve the reliability of decisions about when to auto-analyze. The previous code depended on n_live_tuples + n_dead_tuples - last_anl_tuples, where all three of these numbers could be bad estimates from ANALYZE itself. Even worse, in the presence of a steady flow of HOT updates and matching HOT-tuple reclamations, auto-analyze might never trigger at all, even if all three numbers are exactly right, because n_dead_tuples could hold steady. To fix, replace last_anl_tuples with an accurately tracked count of the total number of committed tuple inserts + updates + deletes since the last ANALYZE on the table. This can still be compared to the same threshold as before, but it's much more trustworthy than the old computation. Tracking this requires one more intra-transaction counter per modified table within backends, but no additional memory space in the stats collector. There probably isn't any measurable speed difference; if anything it might be a bit faster than before, since I was able to eliminate some per-tuple arithmetic operations in favor of adding sums once per (sub)transaction. Also, simplify the logic around pgstat vacuum and analyze reporting messages by not trying to fold VACUUM ANALYZE into a single pgstat message. The original thought behind this patch was to allow scheduling of analyzes on parent tables by artificially inflating their changes_since_analyze count. I've left that for a separate patch since this change seems to stand on its own merit.
2009-12-30 21:32:14 +01:00
2006-10-04 02:30:14 +02:00
if (msg->m_autovacuum)
{
tabentry->autovac_analyze_timestamp = msg->m_analyzetime;
tabentry->autovac_analyze_count++;
}
2006-10-04 02:30:14 +02:00
else
{
tabentry->analyze_timestamp = msg->m_analyzetime;
tabentry->analyze_count++;
}
}
/* ----------
* pgstat_recv_archiver() -
*
* Process a ARCHIVER message.
* ----------
*/
static void
pgstat_recv_archiver(PgStat_MsgArchiver *msg, int len)
{
if (msg->m_failed)
{
/* Failed archival attempt */
++archiverStats.failed_count;
memcpy(archiverStats.last_failed_wal, msg->m_xlog,
sizeof(archiverStats.last_failed_wal));
archiverStats.last_failed_timestamp = msg->m_timestamp;
}
else
{
/* Successful archival operation */
++archiverStats.archived_count;
memcpy(archiverStats.last_archived_wal, msg->m_xlog,
sizeof(archiverStats.last_archived_wal));
archiverStats.last_archived_timestamp = msg->m_timestamp;
}
}
/* ----------
* pgstat_recv_bgwriter() -
*
* Process a BGWRITER message.
* ----------
*/
static void
pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len)
{
globalStats.timed_checkpoints += msg->m_timed_checkpoints;
globalStats.requested_checkpoints += msg->m_requested_checkpoints;
globalStats.checkpoint_write_time += msg->m_checkpoint_write_time;
globalStats.checkpoint_sync_time += msg->m_checkpoint_sync_time;
globalStats.buf_written_checkpoints += msg->m_buf_written_checkpoints;
globalStats.buf_written_clean += msg->m_buf_written_clean;
globalStats.maxwritten_clean += msg->m_maxwritten_clean;
globalStats.buf_written_backend += msg->m_buf_written_backend;
globalStats.buf_fsync_backend += msg->m_buf_fsync_backend;
globalStats.buf_alloc += msg->m_buf_alloc;
}
/* ----------
* pgstat_recv_recoveryconflict() -
*
* Process a RECOVERYCONFLICT message.
* ----------
*/
static void
pgstat_recv_recoveryconflict(PgStat_MsgRecoveryConflict *msg, int len)
{
PgStat_StatDBEntry *dbentry;
2011-04-10 17:42:00 +02:00
dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
switch (msg->m_reason)
{
case PROCSIG_RECOVERY_CONFLICT_DATABASE:
2011-04-10 17:42:00 +02:00
/*
2011-04-10 17:42:00 +02:00
* Since we drop the information about the database as soon as it
* replicates, there is no point in counting these conflicts.
*/
break;
case PROCSIG_RECOVERY_CONFLICT_TABLESPACE:
dbentry->n_conflict_tablespace++;
break;
case PROCSIG_RECOVERY_CONFLICT_LOCK:
dbentry->n_conflict_lock++;
break;
case PROCSIG_RECOVERY_CONFLICT_SNAPSHOT:
dbentry->n_conflict_snapshot++;
break;
case PROCSIG_RECOVERY_CONFLICT_BUFFERPIN:
dbentry->n_conflict_bufferpin++;
break;
case PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK:
dbentry->n_conflict_startup_deadlock++;
break;
}
}
/* ----------
* pgstat_recv_deadlock() -
*
* Process a DEADLOCK message.
* ----------
*/
static void
pgstat_recv_deadlock(PgStat_MsgDeadlock *msg, int len)
{
PgStat_StatDBEntry *dbentry;
dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
dbentry->n_deadlocks++;
}
/* ----------
* pgstat_recv_tempfile() -
*
* Process a TEMPFILE message.
* ----------
*/
static void
pgstat_recv_tempfile(PgStat_MsgTempFile *msg, int len)
{
PgStat_StatDBEntry *dbentry;
dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
dbentry->n_temp_bytes += msg->m_filesize;
dbentry->n_temp_files += 1;
}
/* ----------
* pgstat_recv_funcstat() -
*
* Count what the backend has done.
* ----------
*/
static void
pgstat_recv_funcstat(PgStat_MsgFuncstat *msg, int len)
{
PgStat_FunctionEntry *funcmsg = &(msg->m_entry[0]);
PgStat_StatDBEntry *dbentry;
PgStat_StatFuncEntry *funcentry;
int i;
bool found;
dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
/*
* Process all function entries in the message.
*/
for (i = 0; i < msg->m_nentries; i++, funcmsg++)
{
funcentry = (PgStat_StatFuncEntry *) hash_search(dbentry->functions,
(void *) &(funcmsg->f_id),
HASH_ENTER, &found);
if (!found)
{
/*
* If it's a new function entry, initialize counters to the values
* we just got.
*/
funcentry->f_numcalls = funcmsg->f_numcalls;
funcentry->f_total_time = funcmsg->f_total_time;
funcentry->f_self_time = funcmsg->f_self_time;
}
else
{
/*
* Otherwise add the values to the existing entry.
*/
funcentry->f_numcalls += funcmsg->f_numcalls;
funcentry->f_total_time += funcmsg->f_total_time;
funcentry->f_self_time += funcmsg->f_self_time;
}
}
}
/* ----------
* pgstat_recv_funcpurge() -
*
* Arrange for dead function removal.
* ----------
*/
static void
pgstat_recv_funcpurge(PgStat_MsgFuncpurge *msg, int len)
{
PgStat_StatDBEntry *dbentry;
int i;
dbentry = pgstat_get_db_entry(msg->m_databaseid, false);
/*
* No need to purge if we don't even know the database.
*/
if (!dbentry || !dbentry->functions)
return;
/*
* Process all function entries in the message.
*/
for (i = 0; i < msg->m_nentries; i++)
{
/* Remove from hashtable if present; we don't care if it's not. */
(void) hash_search(dbentry->functions,
(void *) &(msg->m_functionid[i]),
HASH_REMOVE, NULL);
}
}
/* ----------
* pgstat_write_statsfile_needed() -
*
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
* Do we need to write out any stats files?
* ----------
*/
static bool
pgstat_write_statsfile_needed(void)
{
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
if (pending_write_requests != NIL)
return true;
/* Everything was written recently */
return false;
}
/* ----------
* pgstat_db_requested() -
*
* Checks whether stats for a particular DB need to be written to a file.
* ----------
*/
static bool
pgstat_db_requested(Oid databaseid)
{
/*
* If any requests are outstanding at all, we should write the stats for
* shared catalogs (the "database" with OID 0). This ensures that
* backends will see up-to-date stats for shared catalogs, even though
* they send inquiry messages mentioning only their own DB.
*/
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
if (databaseid == InvalidOid && pending_write_requests != NIL)
return true;
/* Search to see if there's an open request to write this database. */
Avoid useless closely-spaced writes of statistics files. The original intent in the stats collector was that we should not write out stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not make requests at all if they see the existing data is newer than that, and the stats collector is supposed to disregard requests having a cutoff_time older than its most recently written data, so that close-together requests don't result in multiple writes. But the latter part of that got broken in commit 187492b6c2e8cafc, so that if two backends concurrently decide the existing stats are too old, the collector would write the data twice. (In principle the collector's logic would still merge requests as long as the second one arrives before we've actually written data ... but since the message collection loop would write data immediately after processing a single inquiry message, that never happened in practice, and in any case the window in which it might work would be much shorter than PGSTAT_STAT_INTERVAL.) To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff time is too old, and doesn't add a request to the queue if so. This means that we do not need DBWriteRequest.request_time, because the decision is taken before making a queue entry. And that means that we don't really need the DBWriteRequest data structure at all; an OID list of database OIDs will serve and allow removal of some rather verbose and crufty code. In passing, improve the comments in this area, which have been rather neglected. Also change backend_read_statsfile so that it's not silently relying on MyDatabaseId to have some particular value in the autovacuum launcher process. It accidentally worked as desired because MyDatabaseId is zero in that process; but that does not seem like a dependency we want, especially with no documentation about it. Although this patch is mine, it turns out I'd rediscovered a known bug, for which Tomas Vondra had already submitted a patch that's functionally equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas for reviewing this version. Back-patch to 9.3 where the bug was introduced. Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz> Patch: <4625.1464202586@sss.pgh.pa.us>
2016-05-31 21:54:46 +02:00
if (list_member_oid(pending_write_requests, databaseid))
return true;
return false;
}
/*
* Convert a potentially unsafely truncated activity string (see
* PgBackendStatus.st_activity_raw's documentation) into a correctly truncated
* one.
*
* The returned string is allocated in the caller's memory context and may be
* freed.
*/
char *
pgstat_clip_activity(const char *raw_activity)
{
char *activity;
int rawlen;
int cliplen;
/*
* Some callers, like pgstat_get_backend_current_activity(), do not
* guarantee that the buffer isn't concurrently modified. We try to take
* care that the buffer is always terminated by a NUL byte regardless, but
* let's still be paranoid about the string's length. In those cases the
* underlying buffer is guaranteed to be pgstat_track_activity_query_size
* large.
*/
activity = pnstrdup(raw_activity, pgstat_track_activity_query_size - 1);
/* now double-guaranteed to be NUL terminated */
rawlen = strlen(activity);
/*
* All supported server-encodings make it possible to determine the length
* of a multi-byte character from its first byte (this is not the case for
* client encodings, see GB18030). As st_activity is always stored using
* server encoding, this allows us to perform multi-byte aware truncation,
* even if the string earlier was truncated in the middle of a multi-byte
* character.
*/
cliplen = pg_mbcliplen(activity, rawlen,
pgstat_track_activity_query_size - 1);
activity[cliplen] = '\0';
return activity;
}