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Suppress log spam from multiple reports of SIGQUIT shutdown.

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When the postmaster sends SIGQUIT to its children, there's no real
need for all the children to log that fact; the postmaster already
made a log entry about it, so adding perhaps dozens or hundreds of
child-process log entries adds nothing of value.  So, let's introduce
a new ereport level to specify "WARNING, but never send to log" and
use that for these messages.

Such a change wouldn't have been desirable before commit 7e784d1dc,
because if someone manually SIGQUIT's a backend, we *do* want to log
that.  But now we can tell the difference between a signal that was
issued by the postmaster and one that was not with reasonable
certainty.

While we're here, also clear error_context_stack before ereport'ing,
to prevent error callbacks from being invoked in the signal-handler
context.  This should reduce the odds of getting hung up while trying
to notify the client.

Per a suggestion from Andres Freund.

Discussion: https://postgr.es/m/20201225230331.hru3u6obyy6j53tk@alap3.anarazel.de
This commit is contained in:
Tom Lane
2020-12-29 18:02:38 -05:00
parent db6335b5b1
commit 1f9158ba48
3 changed files with 29 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
src/backend/tcop/postgres.c
View File

@ -2789,6 +2789,18 @@ quickdie(SIGNAL_ARGS)
* wrong, so there's not much to lose. Assuming the postmaster is still
* running, it will SIGKILL us soon if we get stuck for some reason.
*
* One thing we can do to make this a tad safer is to clear the error
* context stack, so that context callbacks are not called. That's a lot
* less code that could be reached here, and the context info is unlikely
* to be very relevant to a SIGQUIT report anyway.
*/
error_context_stack = NULL;
/*
* When responding to a postmaster-issued signal, we send the message only
* to the client; sending to the server log just creates log spam, plus
* it's more code that we need to hope will work in a signal handler.
*
* Ideally these should be ereport(FATAL), but then we'd not get control
* back to force the correct type of process exit.
*/
@ -2802,7 +2814,7 @@ quickdie(SIGNAL_ARGS)
break;
case PMQUIT_FOR_CRASH:
/* A crash-and-restart cycle is in progress */
ereport(WARNING,
ereport(WARNING_CLIENT_ONLY,
(errcode(ERRCODE_CRASH_SHUTDOWN),
errmsg("terminating connection because of crash of another server process"),
errdetail("The postmaster has commanded this server process to roll back"
@ -2814,7 +2826,7 @@ quickdie(SIGNAL_ARGS)
break;
case PMQUIT_FOR_STOP:
/* Immediate-mode stop */
ereport(WARNING,
ereport(WARNING_CLIENT_ONLY,
(errcode(ERRCODE_ADMIN_SHUTDOWN),
errmsg("terminating connection due to immediate shutdown command")));
break;

10
src/backend/utils/error/elog.c
View File

@ -202,6 +202,11 @@ is_log_level_output(int elevel, int log_min_level)
if (log_min_level == LOG || log_min_level <= ERROR)
return true;
}
else if (elevel == WARNING_CLIENT_ONLY)
{
/* never sent to log, regardless of log_min_level */
return false;
}
else if (log_min_level == LOG)
{
/* elevel != LOG */
@ -453,7 +458,7 @@ errstart(int elevel, const char *domain)
/* Select default errcode based on elevel */
if (elevel >= ERROR)
edata->sqlerrcode = ERRCODE_INTERNAL_ERROR;
else if (elevel == WARNING)
else if (elevel >= WARNING)
edata->sqlerrcode = ERRCODE_WARNING;
else
edata->sqlerrcode = ERRCODE_SUCCESSFUL_COMPLETION;
@ -2152,6 +2157,7 @@ write_eventlog(int level, const char *line, int len)
eventlevel = EVENTLOG_INFORMATION_TYPE;
break;
case WARNING:
case WARNING_CLIENT_ONLY:
eventlevel = EVENTLOG_WARNING_TYPE;
break;
case ERROR:
@ -3109,6 +3115,7 @@ send_message_to_server_log(ErrorData *edata)
break;
case NOTICE:
case WARNING:
case WARNING_CLIENT_ONLY:
syslog_level = LOG_NOTICE;
break;
case ERROR:
@ -3484,6 +3491,7 @@ error_severity(int elevel)
prefix = gettext_noop("NOTICE");
break;
case WARNING:
case WARNING_CLIENT_ONLY:
prefix = gettext_noop("WARNING");
break;
case ERROR: