Subject: Re: postgres_fdw test timeouts

From: Thomas Munro <[email-masked]>
Date: Sun, 3 Dec 2023 12:48:49 +1300

On Fri, Dec 1, 2023 at 9:38 AM Nathan Bossart <[email-masked]> wrote:
> AFAICT the failures began around September 10th, which leads me to wonder
> if this is related to commit 04a09ee.  That is little more than a wild
> guess, though.  I haven't been able to deduce much else from the logs I can
> find, and I didn't find any previous reports about this in the archives
> after lots of searching, so I thought I'd at least park these notes here in
> case anyone else has ideas.

Thanks for finding this correlation.  Yeah, poking around in the cfbot
history database I see about 1 failure like that per day since that
date, and there doesn't seem to be anything else as obviously likely
to be related to wakeups and timeouts.  I don't understand what's
wrong with the logic, and I think it would take someone willing to
debug it locally to figure that out.  Unless someone has an idea, I'm
leaning towards reverting that commit and leaving the relatively minor
problem that it was intended to fix as a TODO.

---

From: Alexander Lakhin <[email-masked]>
Date: Sun, 3 Dec 2023 08:00:00 +0300

Hello Thomas,

03.12.2023 02:48, Thomas Munro wrote:
> problem that it was intended to fix as a TODO

I've managed to reproduce the failure locally when running postgres_fdw_x/
regress in parallel (--num-processes 10). It reproduced for me on
on 04a09ee94 (iterations 1, 2, 4), but not on 04a09ee94~1 (30 iterations
passed).

I'm going to investigate this case within days. Maybe we could find a
better fix for the issue.

Best regards,
Alexander