Lots of stuck queries after upgrade to 9.4, possible race condition
I forward here from PG general list. Stack traces included.
---------- Forwarded message ----------
From: Spiros Ioannou <sivann@inaccess.com>
Date: 20 July 2015 at 13:16
Subject: Re: [GENERAL] Lots of stuck queries after upgrade to 9.4
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: "pgsql-general@postgresql.org" <pgsql-general@postgresql.org>
Date: 20 July 2015 at 13:16
Subject: Re: [GENERAL] Lots of stuck queries after upgrade to 9.4
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: "pgsql-general@postgresql.org" <pgsql-general@postgresql.org>
Hi Tom,
thank you for your input. The DB was stuck again, I attach all logs and stack traces.
A stack trace from a COMMIT, an INSERT, an UPDATE, the wal writer, the writer, and a sequence.
Stracing the commit was stuck at: semop(3145761, {{12, -1, 0}}, 1
Please tell me what else could I do to help debugging.
Is there a way to downgrade postgresql ?
On 20 July 2015 at 01:01, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Spiros Ioannou <sivann@inaccess.com> writes:
> We upgraded to 9.4.4 from 8.4 We have tried 9.3.x in the past with success.
> Unfortunately in 9.4 gets stuck 2-3 times a week.
> Lots of queries seem stuck, that is they have waiting:false. Queries can be
> COMMIT or INSERT.
> No blocking locks seem to exist.
> strace reveals that all stuck processes they are in semop
> semop(2064417, {{0, -1, 0}}, 1^C <unfinished ...>
Stack traces of the stuck processes might help determine what's going on.
https://wiki.postgresql.org/wiki/Generating_a_stack_trace_of_a_PostgreSQL_backend
Please try to capture traces for both the COMMIT and INSERT cases,
as they're almost certainly different.
regards, tom lane
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