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Speedup and increase usability of set proc title functions

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

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);