Re: Add wait event for log emission?

At Tue, 13 Jun 2023 17:18:58 -0700, Andres Freund <andres@anarazel.de> wrote in 
> Hi,
> 
> On 2023-06-13 20:55:19 +0200, Magnus Hagander wrote:
> > On Tue, Jun 13, 2023 at 6:59 PM Andres Freund <andres@anarazel.de> wrote:
> > > I think we should add a few wait events for log emission. I think it'd be good
> > > to have one wait event for each log destination.
> > >
> > > That's not perfect - we'd e.g. still not be able to debug where the logger
> > > process is stuck, due it not being in pg_stat_activity. But other processes
> > > reporting the wait event for writing to the logger process would be a pretty
> > > good hint.
> > 
> > 
> > +1.
> > 
> > Would it make sense to at the same time create a separate one for
> > syslog, or just use the same?
> 
> I think it should be a separate one for each of the log paths in
> send_message_to_server_log(). I don't think we gain anything by being stingy
> here - and it's not like we add one every other day.
> 
> I do wonder if it'd be worth setting up a wait event around emit_log_hook -
> it's somewhat of a misuse of wait events, but might be useful nonetheless?

We are already doing something similar for archive_command. Given that
the execution time of this hook is unpredictable, it seems resonable
to me to do that there. Essentially, we are "waiting" for the
hook-function to return.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center