From: | Pavel Suderevsky <psuderevsky(at)gmail(dot)com> |
---|---|
To: | Postgres General <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: 9.6.11- could not truncate directory "pg_serial": apparent wraparound |
Date: | 2019-04-06 14:31:08 |
Message-ID: | CAEBTBzt24tEsCkupOCxUvy=hnvMnZ59aXECoMAOyAO6iFmhTBg@mail.gmail.com |
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Lists: | pgsql-general |
Guys, still need your help.
Previous night:
*2019-04-05 00:35:04 UTC LOG: could not truncate directory "pg_serial":
apparent wraparound*
*2019-04-05 00:40:04 UTC LOG: could not truncate directory "pg_serial":
apparent wraparound*
(2 checkpoints)
It turned that I have some problem with performance related to predicate
locking on this platform.
A lot of long prepared statements with the *SerializableXactHashLock* and
*predicate_lock_manager* wait_events followed by high CPU usage happened
during 00:30 and 00:45. During this period there were 55k pred locks
granted at max and 30k in average. Probably because of high CPU usage some
statements were spending a lot of time in bind/parse steps.
Probably if you advise me what could cause *"pg_serial": apparent
wraparound* messages I would have more chances to handle all the
performance issues.
Thank you!
--
Pavel Suderevsky
E: psuderevsky(at)gmail(dot)com
пн, 11 мар. 2019 г. в 19:09, Pavel Suderevsky <psuderevsky(at)gmail(dot)com>:
> Hi,
>
> PG: 9.6.11
> OS: CentOS
> Env: AWS EC2
>
> I've faced the following exceptions in PostgreSQL server log:
> > could not truncate directory "pg_serial": apparent wraparound
> Sometimes it repeats every 5 min and the longest period was 40 min.
>
> In fact, I can't find any suspicious events happening that periods.
> pg_wait_sampling didn't catch any events, no long queries (more than 60s),
> Autovacuum workers or transactions in "idle in transaction" state were in
> action at this time.
>
> The only related I could find in archive is:
> https://www.postgresql.org/message-id/CACjxUsON4Vya3a6r%3DubwmN-4qTDDfZjuwSzjnL1QjdUc8_gzLw%40mail.gmail.com
> >You should not see the errors you are reporting nor
> >the warning I mentioned unless a serializable transaction remains
> >active long enough for about 1 billion transaction IDs to be
> >consumed.
>
> Database age now is just 18.5 millions of transactions.
>
> Server has two standbys (sync and async), hot_standby_feedback is off.
>
> Please advice what I can do to find a reason of these exceptions.
>
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