Zdenek Kotala wrote:
> Just a confirmation that Alvaro's patch+ReleasePostmasterChildSlot() fix
> solves the problem and PostgreSQL survives well during a memory
> shortages.
So this patch would do it.
I think this stuff about postmaster child slots is later than
launcher/worker split. I don't recall seeing it before.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
Index: src/backend/postmaster/postmaster.c
===================================================================
RCS file: /home/alvherre/Code/cvs/pgsql/src/backend/postmaster/postmaster.c,v
retrieving revision 1.587
diff -c -p -r1.587 postmaster.c
*** src/backend/postmaster/postmaster.c 7 Aug 2009 05:58:55 -0000 1.587
--- src/backend/postmaster/postmaster.c 24 Aug 2009 15:05:50 -0000
*************** bool redirection_done = false; /* stder
*** 290,295 ****
--- 290,297 ----
/* received START_AUTOVAC_LAUNCHER signal */
static volatile sig_atomic_t start_autovac_launcher = false;
+ /* the launcher needs to be signalled to communicate some condition */
+ static volatile bool avlauncher_needs_signal = false;
/*
* State for assigning random salts and cancel keys.
*************** ServerLoop(void)
*** 1391,1396 ****
--- 1393,1406 ----
if (PgStatPID == 0 && pmState == PM_RUN)
PgStatPID = pgstat_start();
+ /* If we need to signal the autovacuum launcher, do so now */
+ if (avlauncher_needs_signal)
+ {
+ avlauncher_needs_signal = false;
+ if (AutoVacPID != 0)
+ kill(AutoVacPID, SIGUSR1);
+ }
+
/*
* Touch the socket and lock file every 58 minutes, to ensure that
* they are not removed by overzealous /tmp-cleaning tasks. We assume
*************** StartAutovacuumWorker(void)
*** 4343,4348 ****
--- 4353,4359 ----
* fork failed, fall through to report -- actual error message was
* logged by StartAutoVacWorker
*/
+ ReleasePostmasterChildSlot(bn->child_slot);
free(bn);
}
else
*************** StartAutovacuumWorker(void)
*** 4354,4365 ****
/*
* Report the failure to the launcher, if it's running. (If it's not, we
* might not even be connected to shared memory, so don't try to call
! * AutoVacWorkerFailed.)
*/
if (AutoVacPID != 0)
{
AutoVacWorkerFailed();
! kill(AutoVacPID, SIGUSR1);
}
}
--- 4365,4380 ----
/*
* Report the failure to the launcher, if it's running. (If it's not, we
* might not even be connected to shared memory, so don't try to call
! * AutoVacWorkerFailed.) Note that we also need to signal it so that it
! * responds to the condition, but we don't do that here, instead waiting
! * for ServerLoop to do it. This way we avoid a ping-pong signalling in
! * quick succession between the autovac launcher and postmaster in case
! * things get ugly.
*/
if (AutoVacPID != 0)
{
AutoVacWorkerFailed();
! avlauncher_needs_signal = true;
}
}
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