Re: Why does [auto-]vacuum delay not report a wait event?

On Fri, Mar 20, 2020 at 12:32 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Fri, Mar 20, 2020 at 4:15 AM Andres Freund <andres@anarazel.de> wrote:
> >
> > Hi,
> >
> > I was looking at [1], wanting to suggest a query to monitor what
> > autovacuum is mostly waiting on. Partially to figure out whether it's
> > mostly autovacuum cost limiting.
> >
> > But uh, unfortunately the vacuum delay code just sleeps without setting
> > a wait event:
> >
> > void
> > vacuum_delay_point(void)
> > {
> > ...
> >         /* Nap if appropriate */
> >         if (msec > 0)
> >         {
> >                 if (msec > VacuumCostDelay * 4)
> >                         msec = VacuumCostDelay * 4;
> >
> >                 pg_usleep((long) (msec * 1000));
> >
> >
> > Seems like it should instead use a new wait event in the PG_WAIT_TIMEOUT
> > class?
> >
>
> +1.  I think it will be quite helpful.

Definite +1. There should be a wait event, and identifying this
particular case is certainly interesting enough that it should have
it's own.

-- 
 Magnus Hagander
 Me: https://www.hagander.net/
 Work: https://www.redpill-linpro.com/