Re: Add wait events for server logging destination writes

Hi,

Thanks Kirk, glad it's useful.

Kyotaro Horiguchi wrote:
> Should we also consider instrumenting ReportEventW()/ReportEventA()?
> They seem to be another Windows-specific logging output path.
>
> Also, if the intention is to cover all places where logging output
> can block, I wonder whether the syslog() calls should be covered as
> well.

Good points -- both are blocking output paths and there's no real
reason to leave them out, so v3 instruments them rather than excluding
them with a comment. The intent is exactly to cover the places where
logging output can block, so this makes the series consistent.

v3 adds two more WaitEventIO events:

IO / SyslogWrite - syslog(3) in write_syslog()
IO / EventlogWrite - ReportEventW()/ReportEventA() in write_eventlog()

Same approach as before: the wait is reported only around the leaf
call, using the existing pgstat_report_wait_start()/end() helpers, so
it stays allocation-free and safe on the error-reporting path, and the
series still touches just elog.c and wait_event_names.txt.

This also matches Michael's point on v2 -- each event covers a routine
rather than a single call site, so SyslogWrite wraps the syslog(3)
calls in write_syslog() and EventlogWrite wraps both ReportEvent
variants in write_eventlog(), the same way SysloggerWrite already
covers the two writes in write_pipe_chunks().

As before, 0001 is the portable part and 0002 is the Windows part
(WriteConsoleW plus the new EventlogWrite).

One caveat: EventlogWrite is Windows-only, so I couldn't get a runtime
before/after for it here -- I've only confirmed it builds (cfbot's
Windows task should cover that). The other events still show up in the
sampling I posted earlier. If someone on Windows can exercise the
event-log path I'd appreciate a confirmation.

Applies cleanly on current master; full build passes locally on both
Autoconf and Meson, with no new warnings.

Thanks,
Seongjun Shin

2026년 6월 1일 (월) 오후 2:49, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>님이 작성:
>
> Hello.
>
> At Sun, 31 May 2026 17:50:08 +0900, 신성준 <shinsj4653(at)gmail(dot)com> wrote in
> > Attached is a short series that adds two WaitEventIO events and reports
> > them around those writes:
> >
> > IO / SysloggerWrite - write(2) to the syslogger pipe
> > IO / StderrWrite - write(2) to stderr, and WriteConsoleW()
> >
> > 0001 adds the events and covers the write(2) paths. 0002 does the
> > Windows WriteConsoleW() path, split out since it's platform-specific.
>
> Should we also consider instrumenting ReportEventW()/ReportEventA()?
> They seem to be another Windows-specific logging output path.
>
> Also, if the intention is to cover all places where logging output can
> block, I wonder whether the syslog() calls should be covered as
> well. If they are intentionally excluded, perhaps a short comment
> explaining the rationale would be useful.
>
> Regards.
>
> --
> Kyotaro Horiguchi
> NTT Open Source Software Center