Re: Add a perl function in Cluster.pm to generate WAL

07.01.2024 10:10, Michael Paquier wrote:
> On Fri, Jan 05, 2024 at 11:00:00PM +0300, Alexander Lakhin wrote:
>> Your suspicion was proved right. After
>> git show c161ab74f src/test/recovery/t/035_standby_logical_decoding.pl  | git apply -R
>> 20 iterations with 20 tests in parallel performed successfully for me
>> (twice).
>>
>> So it looks like c161ab74f really made the things worse.

After more waiting, I saw the test failure (with c161ab74f reverted) on
iteration 17 in VM where one test run takes up to 800 seconds.

> We have two different failures here, one when VACUUM fails for a
> shared relation:
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2024-01-03%2017%3A09%3A27
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2024-01-01%2020%3A10%3A18
>
> And the second failure happens for VACUUM FULL with a shared relation:
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2024-01-03%2020%3A07%3A15
>
> In the second case, the VACUUM FULL happens *BEFORE* the new
> advance_wal(), making c161ab74f unrelated, no?
>
> Anyway, if one looks at the buildfarm logs, this failure is more
> ancient than c161ab74f. We have many of them before that, some
> reported back in October:
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2023-10-19%2000%3A44%3A58
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2023-10-30%2013%3A39%3A20

Yes, I wrote exactly about that upthread and referenced my previous
investigation. But what I'm observing now, is that the failure probability
greatly increased with c161ab74f, so something really changed in the test
behaviour. (I need a couple of days to investigate this.)

Best regards,
Alexander