Re: test: avoid redundant standby catchup in 049_wait_for_lsn

On Mon, Apr 20, 2026 at 6:21 PM Alexander Korotkov <aekorotkov(at)gmail(dot)com> wrote:
>
> On Sat, Apr 18, 2026 at 10:58 AM Alexander Korotkov
> <aekorotkov(at)gmail(dot)com> wrote:
> > On Sat, Apr 18, 2026 at 7:20 AM Xuneng Zhou <xunengzhou(at)gmail(dot)com> wrote:
> > >> On Fri, Apr 17, 2026 at 08:25:35PM +0800, Xuneng Zhou wrote:
> > >> > The change preserves the same coverage while removing one redundant
> > >> > replay catch-up on the delayed standby. It appears to reduce the test
> > >> > runtime by about 7 seconds, though I have looked into why much of the
> > >> > improvement comes from this change alone.
> > >>
> > >> Alexander may think differently and remove that, but I disagree. The
> > >> test is clearly written so as we want two wait checks to happen, for
> > >> for CREATE FUNCTION, and one for CREATE PROCEDURE. Removing the first
> > >> check to keep only the second one removes its meaning. In short, I
> > >> see nothing wrong to deal with here.
> > >
> > >
> > > Thank you for the review. I agree that the two wait checks serve distinct purposes and are not redundant. The main motivation for this patch was efficiency. In my testing, the new test added approximately 7 seconds to the runtime, while the creation of the procedure and function completed quickly. I suspect the latency stems from the wait-for-catch-up step. When I removed it, the test runtime dropped by about 7 seconds.I haven't yet investigated why the wait is so costly in this case. I should probably look into that before proposing this change.
> >
> > On my laptop the time needed to run t/049_wait_for_lsn.pl also drops
> > from 20 secs to 12 secs. The influence to the runtime of the whole
> > test suite in parallel would be not that big as CPU time only drops
> > from 2.16 sec to 2.07 sec. But anyway that's pretty significant.
> > I've revised comment message a bit and surrounding comments. I'm
> > going to push this if no objections.
>
> Pushed.
>

Thanks for pushing it. I haven't had time to investigate the latency
yet, but will do it later.

Best,
Xuneng