Re: Suppressing useless wakeups in walreceiver

On Mon, Nov 14, 2022 at 12:11 PM Thomas Munro <thomas.munro@gmail.com> wrote:
> On Mon, Nov 14, 2022 at 11:26 AM Nathan Bossart
> <nathandbossart@gmail.com> wrote:
> > On Sun, Nov 13, 2022 at 05:08:04PM -0500, Tom Lane wrote:
> > > There is something very seriously wrong with this patch.
> > >
> > > On my machine, running "make -j10 check-world" (with compilation
> > > already done) has been taking right about 2 minutes for some time.
> > > Since this patch, it's taking around 2:45 --- I did a bisect run
> > > to confirm that this patch is where it changed.
> >
> > I've been looking into this.  I wrote a similar patch for logical/worker.c
> > before noticing that check-world was taking much longer.  The problem in
> > that case seems to be that process_syncing_tables() isn't called as often.
> > It wouldn't surprise me if there's also something in walreceiver.c that
> > depends upon the frequent wakeups.  I suspect this will require a revert.
>
> In the case of "meson test pg_basebackup/020_pg_receivewal" it looks
> like wait_for_catchup hangs around for 10 seconds waiting for HS
> feedback.  I'm wondering if we need to go back to high frequency
> wakeups until it's caught up, or (probably better) arrange for a
> proper event for progress.  Digging...

Maybe there is a better way to code this (I mean, who likes global
variables?) and I need to test some more, but I suspect the attached
is approximately what we missed.