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Add background worker type 

Add bgw_type field to background worker structure.  It is intended to be
set to the same value for all workers of the same type, so they can be
grouped in pg_stat_activity, for example.

The backend_type column in pg_stat_activity now shows bgw_type for a
background worker.  The ps listing also no longer calls out that a
process is a background worker but just show the bgw_type.  That way,
being a background worker is more of an implementation detail now that
is not shown to the user.  However, most log messages still refer to
'background worker "%s"'; otherwise constructing sensible and
translatable log messages would become tricky.

Reviewed-by: Michael Paquier <michael.paquier@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
This commit is contained in:
Peter Eisentraut 2017-08-31 12:24:47 -04:00
parent 8b304b8b72
commit 5373bc2a08
10 changed files with 89 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
contrib/pg_prewarm/autoprewarm.c
View File

@ -800,7 +800,8 @@ apw_start_master_worker(void)
worker.bgw_start_time = BgWorkerStart_ConsistentState;
strcpy(worker.bgw_library_name, "pg_prewarm");
strcpy(worker.bgw_function_name, "autoprewarm_main");
strcpy(worker.bgw_name, "autoprewarm");
strcpy(worker.bgw_name, "autoprewarm master");
strcpy(worker.bgw_type, "autoprewarm master");
if (process_shared_preload_libraries_in_progress)
{
@ -840,7 +841,8 @@ apw_start_database_worker(void)
worker.bgw_start_time = BgWorkerStart_ConsistentState;
strcpy(worker.bgw_library_name, "pg_prewarm");
strcpy(worker.bgw_function_name, "autoprewarm_database_main");
strcpy(worker.bgw_name, "autoprewarm");
strcpy(worker.bgw_name, "autoprewarm worker");
strcpy(worker.bgw_type, "autoprewarm worker");
/* must set notify PID to wait for shutdown */
worker.bgw_notify_pid = MyProcPid;

11
doc/src/sgml/bgworker.sgml
View File

@ -51,6 +51,7 @@ typedef void (*bgworker_main_type)(Datum main_arg);
typedef struct BackgroundWorker
{
char bgw_name[BGW_MAXLEN];
char bgw_type[BGW_MAXLEN];
int bgw_flags;
BgWorkerStartTime bgw_start_time;
int bgw_restart_time; /* in seconds, or BGW_NEVER_RESTART */
@ -64,8 +65,14 @@ typedef struct BackgroundWorker
</para>
<para>
<structfield>bgw_name</> is a string to be used in log messages, process
listings and similar contexts.
<structfield>bgw_name</> and <structfield>bgw_type</structfield> are
strings to be used in log messages, process listings and similar contexts.
<structfield>bgw_type</structfield> should be the same for all background
workers of the same type, so that it is possible to group such workers in a
process listing, for example. <structfield>bgw_name</structfield> on the
other hand can contain additional information about the specific process.
(Typically, the string for <structfield>bgw_name</structfield> will contain
the type somehow, but that is not strictly required.)
</para>
<para>

1
src/backend/access/transam/parallel.c
View File

@ -467,6 +467,7 @@ LaunchParallelWorkers(ParallelContext *pcxt)
memset(&worker, 0, sizeof(worker));
snprintf(worker.bgw_name, BGW_MAXLEN, "parallel worker for PID %d",
MyProcPid);
snprintf(worker.bgw_type, BGW_MAXLEN, "parallel worker");
worker.bgw_flags =
BGWORKER_SHMEM_ACCESS | BGWORKER_BACKEND_DATABASE_CONNECTION
| BGWORKER_CLASS_PARALLEL;

51
src/backend/postmaster/bgworker.c
View File

@ -344,6 +344,8 @@ BackgroundWorkerStateChange(void)
*/
ascii_safe_strlcpy(rw->rw_worker.bgw_name,
slot->worker.bgw_name, BGW_MAXLEN);
ascii_safe_strlcpy(rw->rw_worker.bgw_type,
slot->worker.bgw_type, BGW_MAXLEN);
ascii_safe_strlcpy(rw->rw_worker.bgw_library_name,
slot->worker.bgw_library_name, BGW_MAXLEN);
ascii_safe_strlcpy(rw->rw_worker.bgw_function_name,
@ -630,6 +632,12 @@ SanityCheckBackgroundWorker(BackgroundWorker *worker, int elevel)
return false;
}
/*
* If bgw_type is not filled in, use bgw_name.
*/
if (strcmp(worker->bgw_type, "") == 0)
strcpy(worker->bgw_type, worker->bgw_name);
return true;
}
@ -671,7 +679,7 @@ bgworker_die(SIGNAL_ARGS)
ereport(FATAL,
(errcode(ERRCODE_ADMIN_SHUTDOWN),
errmsg("terminating background worker \"%s\" due to administrator command",
MyBgworkerEntry->bgw_name)));
MyBgworkerEntry->bgw_type)));
}
/*
@ -700,7 +708,6 @@ void
StartBackgroundWorker(void)
{
sigjmp_buf local_sigjmp_buf;
char buf[MAXPGPATH];
BackgroundWorker *worker = MyBgworkerEntry;
bgworker_main_type entrypt;
@ -710,8 +717,7 @@ StartBackgroundWorker(void)
IsBackgroundWorker = true;
/* Identify myself via ps */
snprintf(buf, MAXPGPATH, "bgworker: %s", worker->bgw_name);
init_ps_display(buf, "", "", "");
init_ps_display(worker->bgw_name, "", "", "");
/*
* If we're not supposed to have shared memory access, then detach from
@ -1233,3 +1239,40 @@ LookupBackgroundWorkerFunction(const char *libraryname, const char *funcname)
return (bgworker_main_type)
load_external_function(libraryname, funcname, true, NULL);
}
/*
* Given a PID, get the bgw_type of the background worker. Returns NULL if
* not a valid background worker.
*
* The return value is in static memory belonging to this function, so it has
* to be used before calling this function again. This is so that the caller
* doesn't have to worry about the background worker locking protocol.
*/
const char *
GetBackgroundWorkerTypeByPid(pid_t pid)
{
int slotno;
bool found = false;
static char result[BGW_MAXLEN];
LWLockAcquire(BackgroundWorkerLock, LW_SHARED);
for (slotno = 0; slotno < BackgroundWorkerData->total_slots; slotno++)
{
BackgroundWorkerSlot *slot = &BackgroundWorkerData->slot[slotno];
if (slot->pid > 0 && slot->pid == pid)
{
strcpy(result, slot->worker.bgw_type);
found = true;
break;
}
}
LWLockRelease(BackgroundWorkerLock);
if (!found)
return NULL;
return result;
}

5
src/backend/postmaster/postmaster.c
View File

@ -3117,8 +3117,9 @@ CleanupBackgroundWorker(int pid,
exitstatus = 0;
#endif
snprintf(namebuf, MAXPGPATH, "%s: %s", _("worker process"),
rw->rw_worker.bgw_name);
snprintf(namebuf, MAXPGPATH, _("background worker \"%s\""),
rw->rw_worker.bgw_type);
if (!EXIT_STATUS_0(exitstatus))
{

3
src/backend/replication/logical/launcher.c
View File

@ -422,6 +422,7 @@ retry:
else
snprintf(bgw.bgw_name, BGW_MAXLEN,
"logical replication worker for subscription %u", subid);
snprintf(bgw.bgw_type, BGW_MAXLEN, "logical replication worker");
bgw.bgw_restart_time = BGW_NEVER_RESTART;
bgw.bgw_notify_pid = MyProcPid;
@ -775,6 +776,8 @@ ApplyLauncherRegister(void)
snprintf(bgw.bgw_function_name, BGW_MAXLEN, "ApplyLauncherMain");
snprintf(bgw.bgw_name, BGW_MAXLEN,
"logical replication launcher");
snprintf(bgw.bgw_type, BGW_MAXLEN,
"logical replication launcher");
bgw.bgw_restart_time = 5;
bgw.bgw_notify_pid = 0;
bgw.bgw_main_arg = (Datum) 0;

16
src/backend/utils/adt/pgstatfuncs.c
View File

@ -21,6 +21,7 @@
#include "funcapi.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/bgworker_internals.h"
#include "postmaster/postmaster.h"
#include "storage/proc.h"
#include "storage/procarray.h"
@ -823,8 +824,19 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
}
}
/* Add backend type */
values[17] =
CStringGetTextDatum(pgstat_get_backend_desc(beentry->st_backendType));
if (beentry->st_backendType == B_BG_WORKER)
{
const char *bgw_type;
bgw_type = GetBackgroundWorkerTypeByPid(beentry->st_procpid);
if (bgw_type)
values[17] = CStringGetTextDatum(bgw_type);
else
nulls[17] = true;
}
else
values[17] =
CStringGetTextDatum(pgstat_get_backend_desc(beentry->st_backendType));
}
else
{

2
src/include/postmaster/bgworker.h
View File

@ -88,6 +88,7 @@ typedef enum
typedef struct BackgroundWorker
{
char bgw_name[BGW_MAXLEN];
char bgw_type[BGW_MAXLEN];
int bgw_flags;
BgWorkerStartTime bgw_start_time;
int bgw_restart_time; /* in seconds, or BGW_NEVER_RESTART */
@ -122,6 +123,7 @@ extern BgwHandleStatus GetBackgroundWorkerPid(BackgroundWorkerHandle *handle,
extern BgwHandleStatus WaitForBackgroundWorkerStartup(BackgroundWorkerHandle *handle, pid_t *pid);
extern BgwHandleStatus
WaitForBackgroundWorkerShutdown(BackgroundWorkerHandle *);
extern const char *GetBackgroundWorkerTypeByPid(pid_t pid);
/* Terminate a bgworker */
extern void TerminateBackgroundWorker(BackgroundWorkerHandle *handle);

2
src/test/modules/test_shm_mq/setup.c
View File

@ -219,7 +219,7 @@ setup_background_workers(int nworkers, dsm_segment *seg)
worker.bgw_restart_time = BGW_NEVER_RESTART;
sprintf(worker.bgw_library_name, "test_shm_mq");
sprintf(worker.bgw_function_name, "test_shm_mq_main");
snprintf(worker.bgw_name, BGW_MAXLEN, "test_shm_mq");
snprintf(worker.bgw_type, BGW_MAXLEN, "test_shm_mq");
worker.bgw_main_arg = UInt32GetDatum(dsm_segment_handle(seg));
/* set bgw_notify_pid, so we can detect if the worker stops */
worker.bgw_notify_pid = MyProcPid;

8
src/test/modules/worker_spi/worker_spi.c
View File

@ -111,7 +111,7 @@ initialize_worker_spi(worktable *table)
StartTransactionCommand();
SPI_connect();
PushActiveSnapshot(GetTransactionSnapshot());
pgstat_report_activity(STATE_RUNNING, "initializing spi_worker schema");
pgstat_report_activity(STATE_RUNNING, "initializing worker_spi schema");
/* XXX could we use CREATE SCHEMA IF NOT EXISTS? */
initStringInfo(&buf);
@ -359,7 +359,8 @@ _PG_init(void)
*/
for (i = 1; i <= worker_spi_total_workers; i++)
{
snprintf(worker.bgw_name, BGW_MAXLEN, "worker %d", i);
snprintf(worker.bgw_name, BGW_MAXLEN, "worker_spi worker %d", i);
snprintf(worker.bgw_type, BGW_MAXLEN, "worker_spi");
worker.bgw_main_arg = Int32GetDatum(i);
RegisterBackgroundWorker(&worker);
@ -385,7 +386,8 @@ worker_spi_launch(PG_FUNCTION_ARGS)
worker.bgw_restart_time = BGW_NEVER_RESTART;
sprintf(worker.bgw_library_name, "worker_spi");
sprintf(worker.bgw_function_name, "worker_spi_main");
snprintf(worker.bgw_name, BGW_MAXLEN, "worker %d", i);
snprintf(worker.bgw_name, BGW_MAXLEN, "worker_spi worker %d", i);
snprintf(worker.bgw_type, BGW_MAXLEN, "worker_spi");
worker.bgw_main_arg = Int32GetDatum(i);
/* set bgw_notify_pid so that we can use WaitForBackgroundWorkerStartup */
worker.bgw_notify_pid = MyProcPid;