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Avoid calling kill() in a postmaster signal handler.

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This causes problems when the system load is high, per report from Zdenek
Kotala in <1250860954.1239.114.camel@localhost>; instead of calling kill
directly, have the signal handler set a flag which is checked in ServerLoop.
This way, the handler can return before being called again by a subsequent
signal sent from the autovacuum launcher.  Also, increase the sleep in the
launcher in this failure path to 1 second.

Backpatch to 8.3, which is when the signalling between autovacuum
launcher/postmaster was introduced.

Also, add a couple of ReleasePostmasterChildSlot calls in error paths; this
part backpatched to 8.4 which is when the child slot stuff was introduced.
This commit is contained in:
Alvaro Herrera 2009-08-24 17:23:02 +00:00
parent 9b708f1f57
commit 45f9b4646f
2 changed files with 21 additions and 5 deletions
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4
src/backend/postmaster/autovacuum.c
View File

@ -55,7 +55,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.101 2009/08/12 20:53:30 tgl Exp $
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.102 2009/08/24 17:23:02 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
@ -653,7 +653,7 @@ AutoVacLauncherMain(int argc, char *argv[])
* of a worker will continue to fail in the same way.
*/
AutoVacuumShmem->av_signal[AutoVacForkFailed] = false;
pg_usleep(100000L); /* 100ms */
pg_usleep(1000000L); /* 1s */
SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
continue;
}

22
src/backend/postmaster/postmaster.c
View File

@ -37,7 +37,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.587 2009/08/07 05:58:55 heikki Exp $
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.588 2009/08/24 17:23:02 alvherre Exp $
*
* NOTES
*
@ -290,6 +290,8 @@ bool redirection_done = false; /* stderr redirected for syslogger? */
/* 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.
@ -1391,6 +1393,14 @@ ServerLoop(void)
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
@ -3014,6 +3024,7 @@ BackendStartup(Port *port)
/* in parent, fork failed */
int save_errno = errno;
(void) ReleasePostmasterChildSlot(bn->child_slot);
free(bn);
errno = save_errno;
ereport(LOG,
@ -4343,6 +4354,7 @@ StartAutovacuumWorker(void)
* fork failed, fall through to report -- actual error message was
* logged by StartAutoVacWorker
*/
(void) ReleasePostmasterChildSlot(bn->child_slot);
free(bn);
}
else
@ -4354,12 +4366,16 @@ StartAutovacuumWorker(void)
/*
* 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.)
* 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();
kill(AutoVacPID, SIGUSR1);
avlauncher_needs_signal = true;
}
}