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Speedup and increase usability of set proc title functions 

The setting of the process title could be seen on profiles of very
fast-to-execute queries.  In many locations where we call
set_ps_display() we pass along a string constant, the length of which is
known during compilation.  Here we effectively rename set_ps_display() to
set_ps_display_with_len() and then add a static inline function named
set_ps_display() which calls strlen() on the given string.  This allows
the compiler to optimize away the strlen() call when dealing with
call sites passing a string constant.  We can then also use memcpy()
instead of strlcpy() to copy the string into the destination buffer.
That's significantly faster than strlcpy's byte-at-a-time way of
copying.

Here we also take measures to improve some code which was adjusting the
process title to add a " waiting" suffix to it.  Call sites which require
this can now just call set_ps_display_suffix() to add or adjust the suffix
and call set_ps_display_remove_suffix() to remove it again.

Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/CAApHDvocBvvk-0gWNA2Gohe+sv9fMcv+fK_G+siBKJrgDG4O7g@mail.gmail.com
This commit is contained in:
David Rowley 2023-02-20 16:18:27 +13:00
parent de2aca2885
commit 2cb82e2acf
7 changed files with 200 additions and 96 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
src/backend/replication/syncrep.c
View File

@ -148,8 +148,6 @@ static bool SyncRepQueueIsOrderedByLSN(int mode);
void
SyncRepWaitForLSN(XLogRecPtr lsn, bool commit)
{
char *new_status = NULL;
const char *old_status;
int mode;
/*
@ -216,15 +214,10 @@ SyncRepWaitForLSN(XLogRecPtr lsn, bool commit)
/* Alter ps display to show waiting for sync rep. */
if (update_process_title)
{
int len;
char buffer[32];
old_status = get_ps_display(&len);
new_status = (char *) palloc(len + 32 + 1);
memcpy(new_status, old_status, len);
sprintf(new_status + len, " waiting for %X/%X",
LSN_FORMAT_ARGS(lsn));
set_ps_display(new_status);
new_status[len] = '\0'; /* truncate off " waiting ..." */
sprintf(buffer, "waiting for %X/%X", LSN_FORMAT_ARGS(lsn));
set_ps_display_suffix(buffer);
}
/*
@ -322,12 +315,9 @@ SyncRepWaitForLSN(XLogRecPtr lsn, bool commit)
MyProc->syncRepState = SYNC_REP_NOT_WAITING;
MyProc->waitLSN = 0;
if (new_status)
{
/* Reset ps display */
set_ps_display(new_status);
pfree(new_status);
}
/* reset ps display to remove the suffix */
if (update_process_title)
set_ps_display_remove_suffix();
}
/*

25
src/backend/storage/buffer/bufmgr.c
View File

@ -4302,8 +4302,8 @@ void
LockBufferForCleanup(Buffer buffer)
{
BufferDesc *bufHdr;
char *new_status = NULL;
TimestampTz waitStart = 0;
bool waiting = false;
bool logged_recovery_conflict = false;
Assert(BufferIsPinned(buffer));
@ -4350,11 +4350,11 @@ LockBufferForCleanup(Buffer buffer)
waitStart, GetCurrentTimestamp(),
NULL, false);
/* Report change to non-waiting status */
if (new_status)
if (waiting)
{
set_ps_display(new_status);
pfree(new_status);
/* reset ps display to remove the suffix if we added one */
set_ps_display_remove_suffix();
waiting = false;
}
return;
}
@ -4374,18 +4374,11 @@ LockBufferForCleanup(Buffer buffer)
/* Wait to be signaled by UnpinBuffer() */
if (InHotStandby)
{
/* Report change to waiting status */
if (update_process_title && new_status == NULL)
if (!waiting)
{
const char *old_status;
int len;
old_status = get_ps_display(&len);
new_status = (char *) palloc(len + 8 + 1);
memcpy(new_status, old_status, len);
strcpy(new_status + len, " waiting");
set_ps_display(new_status);
new_status[len] = '\0'; /* truncate off " waiting" */
/* adjust the process title to indicate that it's waiting */
set_ps_display_suffix("waiting");
waiting = true;
}
/*

27
src/backend/storage/ipc/standby.c
View File

@ -362,7 +362,7 @@ ResolveRecoveryConflictWithVirtualXIDs(VirtualTransactionId *waitlist,
bool report_waiting)
{
TimestampTz waitStart = 0;
char *new_status = NULL;
bool waiting = false;
bool logged_recovery_conflict = false;
/* Fast exit, to avoid a kernel call if there's no work to be done. */
@ -400,14 +400,14 @@ ResolveRecoveryConflictWithVirtualXIDs(VirtualTransactionId *waitlist,
pg_usleep(5000L);
}
if (waitStart != 0 && (!logged_recovery_conflict || new_status == NULL))
if (waitStart != 0 && (!logged_recovery_conflict || !waiting))
{
TimestampTz now = 0;
bool maybe_log_conflict;
bool maybe_update_title;
maybe_log_conflict = (log_recovery_conflict_waits && !logged_recovery_conflict);
maybe_update_title = (update_process_title && new_status == NULL);
maybe_update_title = (update_process_title && !waiting);
/* Get the current timestamp if not report yet */
if (maybe_log_conflict || maybe_update_title)
@ -420,15 +420,8 @@ ResolveRecoveryConflictWithVirtualXIDs(VirtualTransactionId *waitlist,
if (maybe_update_title &&
TimestampDifferenceExceeds(waitStart, now, 500))
{
const char *old_status;
int len;
old_status = get_ps_display(&len);
new_status = (char *) palloc(len + 8 + 1);
memcpy(new_status, old_status, len);
strcpy(new_status + len, " waiting");
set_ps_display(new_status);
new_status[len] = '\0'; /* truncate off " waiting" */
set_ps_display_suffix("waiting");
waiting = true;
}
/*
@ -456,12 +449,10 @@ ResolveRecoveryConflictWithVirtualXIDs(VirtualTransactionId *waitlist,
LogRecoveryConflict(reason, waitStart, GetCurrentTimestamp(),
NULL, false);
/* Reset ps display if we changed it */
if (new_status)
{
set_ps_display(new_status);
pfree(new_status);
}
/* reset ps display to remove the suffix if we added one */
if (waiting)
set_ps_display_remove_suffix();
}
/*

32
src/backend/storage/lmgr/lock.c
View File

@ -1810,24 +1810,12 @@ WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
{
LOCKMETHODID lockmethodid = LOCALLOCK_LOCKMETHOD(*locallock);
LockMethod lockMethodTable = LockMethods[lockmethodid];
char *volatile new_status = NULL;
LOCK_PRINT("WaitOnLock: sleeping on lock",
locallock->lock, locallock->tag.mode);
/* Report change to waiting status */
if (update_process_title)
{
const char *old_status;
int len;
old_status = get_ps_display(&len);
new_status = (char *) palloc(len + 8 + 1);
memcpy(new_status, old_status, len);
strcpy(new_status + len, " waiting");
set_ps_display(new_status);
new_status[len] = '\0'; /* truncate off " waiting" */
}
/* adjust the process title to indicate that it's waiting */
set_ps_display_suffix("waiting");
awaitedLock = locallock;
awaitedOwner = owner;
@ -1874,12 +1862,8 @@ WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
{
/* In this path, awaitedLock remains set until LockErrorCleanup */
/* Report change to non-waiting status */
if (update_process_title)
{
set_ps_display(new_status);
pfree(new_status);
}
/* reset ps display to remove the suffix */
set_ps_display_remove_suffix();
/* and propagate the error */
PG_RE_THROW();
@ -1888,12 +1872,8 @@ WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
awaitedLock = NULL;
/* Report change to non-waiting status */
if (update_process_title)
{
set_ps_display(new_status);
pfree(new_status);
}
/* reset ps display to remove the suffix */
set_ps_display_remove_suffix();
LOCK_PRINT("WaitOnLock: wakeup on lock",
locallock->lock, locallock->tag.mode);

11
src/backend/tcop/postgres.c
View File

@ -1071,6 +1071,8 @@ exec_simple_query(const char *query_string)
Portal portal;
DestReceiver *receiver;
int16 format;
const char *cmdtagname;
size_t cmdtaglen;
pgstat_report_query_id(0, true);
@ -1081,8 +1083,9 @@ exec_simple_query(const char *query_string)
* destination.
*/
commandTag = CreateCommandTag(parsetree->stmt);
cmdtagname = GetCommandTagNameAndLen(commandTag, &cmdtaglen);
set_ps_display(GetCommandTagName(commandTag));
set_ps_display_with_len(cmdtagname, cmdtaglen);
BeginCommand(commandTag, dest);
@ -2064,6 +2067,8 @@ exec_execute_message(const char *portal_name, long max_rows)
char msec_str[32];
ParamsErrorCbData params_data;
ErrorContextCallback params_errcxt;
const char *cmdtagname;
size_t cmdtaglen;
/* Adjust destination to tell printtup.c what to do */
dest = whereToSendOutput;
@ -2110,7 +2115,9 @@ exec_execute_message(const char *portal_name, long max_rows)
pgstat_report_activity(STATE_RUNNING, sourceText);
set_ps_display(GetCommandTagName(portal->commandTag));
cmdtagname = GetCommandTagNameAndLen(portal->commandTag, &cmdtaglen);
set_ps_display_with_len(cmdtagname, cmdtaglen);
if (save_log_statement_stats)
ResetUsage();

162
src/backend/utils/misc/ps_status.c
View File

@ -86,6 +86,14 @@ static size_t ps_buffer_cur_len; /* nominal strlen(ps_buffer) */
static size_t ps_buffer_fixed_size; /* size of the constant prefix */
/*
* Length of ps_buffer before the suffix was appeneded to the end, or 0 if we
* didn't set a suffix.
*/
static size_t ps_buffer_nosuffix_len;
static void flush_ps_display(void);
#endif /* not PS_USE_NONE */
/* save the original argv[] location here */
@ -300,37 +308,158 @@ init_ps_display(const char *fixed_part)
#endif /* not PS_USE_NONE */
}
/*
* Call this to update the ps status display to a fixed prefix plus an
* indication of what you're currently doing passed in the argument.
*/
void
set_ps_display(const char *activity)
{
#ifndef PS_USE_NONE
/*
* update_ps_display_precheck
* Helper function to determine if updating the process title is
* something that we need to do.
*/
static bool
update_ps_display_precheck(void)
{
/* update_process_title=off disables updates */
if (!update_process_title)
return;
return false;
/* no ps display for stand-alone backend */
if (!IsUnderPostmaster)
return;
return false;
#ifdef PS_USE_CLOBBER_ARGV
/* If ps_buffer is a pointer, it might still be null */
if (!ps_buffer)
return;
return false;
#endif
return true;
}
#endif /* not PS_USE_NONE */
/*
* set_ps_display_suffix
* Adjust the process title to append 'suffix' onto the end with a space
* between it and the current process title.
*/
void
set_ps_display_suffix(const char *suffix)
{
#ifndef PS_USE_NONE
size_t len;
/* first, check if we need to update the process title */
if (!update_ps_display_precheck())
return;
/* if there's already a suffix, overwrite it */
if (ps_buffer_nosuffix_len > 0)
ps_buffer_cur_len = ps_buffer_nosuffix_len;
else
ps_buffer_nosuffix_len = ps_buffer_cur_len;
len = strlen(suffix);
/* check if we have enough space to append the suffix */
if (ps_buffer_cur_len + len + 1 >= ps_buffer_size)
{
/* not enough space. Check the buffer isn't full already */
if (ps_buffer_cur_len < ps_buffer_size - 1)
{
/* append a space before the suffix */
ps_buffer[ps_buffer_cur_len++] = ' ';
/* just add what we can and fill the ps_buffer */
memcpy(ps_buffer + ps_buffer_cur_len, suffix,
ps_buffer_size - ps_buffer_cur_len - 1);
ps_buffer[ps_buffer_size - 1] = '\0';
ps_buffer_cur_len = ps_buffer_size - 1;
}
}
else
{
ps_buffer[ps_buffer_cur_len++] = ' ';
memcpy(ps_buffer + ps_buffer_cur_len, suffix, len + 1);
ps_buffer_cur_len = ps_buffer_cur_len + len;
}
Assert(strlen(ps_buffer) == ps_buffer_cur_len);
/* and set the new title */
flush_ps_display();
#endif /* not PS_USE_NONE */
}
/*
* set_ps_display_remove_suffix
* Remove the process display suffix added by set_ps_display_suffix
*/
void
set_ps_display_remove_suffix(void)
{
#ifndef PS_USE_NONE
/* first, check if we need to update the process title */
if (!update_ps_display_precheck())
return;
/* check we added a suffix */
if (ps_buffer_nosuffix_len == 0)
return; /* no suffix */
/* remove the suffix from ps_buffer */
ps_buffer[ps_buffer_nosuffix_len] = '\0';
ps_buffer_cur_len = ps_buffer_nosuffix_len;
ps_buffer_nosuffix_len = 0;
Assert(ps_buffer_cur_len == strlen(ps_buffer));
/* and set the new title */
flush_ps_display();
#endif /* not PS_USE_NONE */
}
/*
* Call this to update the ps status display to a fixed prefix plus an
* indication of what you're currently doing passed in the argument.
*
* 'len' must be the same as strlen(activity)
*/
void
set_ps_display_with_len(const char *activity, size_t len)
{
Assert(strlen(activity) == len);
#ifndef PS_USE_NONE
/* first, check if we need to update the process title */
if (!update_ps_display_precheck())
return;
/* wipe out any suffix when the title is completely changed */
ps_buffer_nosuffix_len = 0;
/* Update ps_buffer to contain both fixed part and activity */
strlcpy(ps_buffer + ps_buffer_fixed_size, activity,
ps_buffer_size - ps_buffer_fixed_size);
ps_buffer_cur_len = strlen(ps_buffer);
if (ps_buffer_fixed_size + len >= ps_buffer_size)
{
/* handle the case where ps_buffer doesn't have enough space */
memcpy(ps_buffer + ps_buffer_fixed_size, activity,
ps_buffer_size - ps_buffer_fixed_size - 1);
ps_buffer[ps_buffer_size - 1] = '\0';
ps_buffer_cur_len = ps_buffer_size - 1;
}
else
{
memcpy(ps_buffer + ps_buffer_fixed_size, activity, len + 1);
ps_buffer_cur_len = ps_buffer_fixed_size + len;
}
Assert(strlen(ps_buffer) == ps_buffer_cur_len);
/* Transmit new setting to kernel, if necessary */
flush_ps_display();
#endif /* not PS_USE_NONE */
}
#ifndef PS_USE_NONE
static void
flush_ps_display(void)
{
#ifdef PS_USE_SETPROCTITLE
setproctitle("%s", ps_buffer);
#elif defined(PS_USE_SETPROCTITLE_FAST)
@ -363,9 +492,8 @@ set_ps_display(const char *activity)
ident_handle = CreateEvent(NULL, TRUE, FALSE, name);
}
#endif /* PS_USE_WIN32 */
#endif /* not PS_USE_NONE */
}
#endif /* not PS_USE_NONE */
/*
* Returns what's currently in the ps display, in case someone needs

17
src/include/utils/ps_status.h
View File

@ -25,7 +25,22 @@ extern char **save_ps_display_args(int argc, char **argv);
extern void init_ps_display(const char *fixed_part);
extern void set_ps_display(const char *activity);
extern void set_ps_display_suffix(const char *suffix);
extern void set_ps_display_remove_suffix(void);
extern void set_ps_display_with_len(const char *activity, size_t len);
/*
* set_ps_display
* inlined to allow strlen to be evaluated during compilation when
* passing string constants.
*/
static inline void
set_ps_display(const char *activity)
{
set_ps_display_with_len(activity, strlen(activity));
}
extern const char *get_ps_display(int *displen);