From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@postgresql.org,
        Thomas Munro <thomas.munro@gmail.com>
Subject: Re: failures in t/031_recovery_conflict.pl on CI
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Mon, 02 May 2022 21:05:57 -0700"
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Date: Tue, 03 May 2022 01:16:46 -0400
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Andres Freund <andres@anarazel.de> writes:
> On 2022-05-02 23:44:32 -0400, Tom Lane wrote:
>> I can poke into that tomorrow, but are you sure that that isn't an
>> expectable result?

> It's not expected. But I think I might see what the problem is:
> We wait for the FETCH (and thus the buffer pin to be acquired). But that
> doesn't guarantee that the lock has been acquired. We can't check that with
> pump_until() afaics, because there'll not be any output. But a query_until()
> checking pg_locks should do the trick?

Irritatingly, it doesn't reproduce (at least not easily) in a manual
build on the same box.  So it's almost surely a timing issue, and
your theory here seems plausible.

			regards, tom lane