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Speedup and increase usability of set proc title functions

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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
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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);