From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
---|---|
To: | Ajin Cherian <itsajin(at)gmail(dot)com> |
Cc: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Failure of subscription tests with topminnow |
Date: | 2021-08-26 03:06:24 |
Message-ID: | CAA4eK1Lmna_w-kWrxKcRwQFB4ZA5xutcV68ev=-tJm7_7psKDA@mail.gmail.com |
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On Thu, Aug 26, 2021 at 7:38 AM Ajin Cherian <itsajin(at)gmail(dot)com> wrote:
>
> On Thu, Aug 26, 2021 at 11:02 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
>
> Luckily these logs have the disconnection times of the tap test client
> sessions as well. (not sure why I don't see these when I run these
> tests).
>
> Step 5 could have happened anywhere between 18:44:38.016 and 18:44:38.063
> 18:44:38.016 CEST [16474:3] 001_rep_changes.pl LOG: statement: SELECT
> pid != 16336 FROM pg_stat_replication WHERE application_name =
> 'tap_sub';
> :
> :
> 18:44:38.063 CEST [16474:4] 001_rep_changes.pl LOG: disconnection:
> session time: 0:00:00.063 user=nm database=postgres host=[local]
>
> When the query starts both walsenders are present but when the query
> completes both walsenders are gone, the actual query evaluation could
> have happened any time in between. This is the rare timing window that
> causes this problem.
>
You have a point but if we see the below logs, it seems the second
walsender (#step6) seemed to exited before the first walsender
(#step4).
2021-08-15 18:44:38.041 CEST [16475:10] tap_sub LOG: disconnection:
session time: 0:00:00.036 user=nm database=postgres host=[local]
2021-08-15 18:44:38.043 CEST [16336:14] tap_sub LOG: disconnection:
session time: 0:00:06.367 user=nm database=postgres host=[local]
Isn't it possible that pid is cleared in the other order due to which
we are seeing this problem?
--
With Regards,
Amit Kapila.
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