From: | Andomar <andomar(at)aule(dot)net> |
---|---|
To: | Qingqing Zhou <zhouqq(dot)postgres(at)gmail(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Waiting on ExclusiveLock on extension |
Date: | 2015-04-17 08:01:05 |
Message-ID: | 5530BDC1.1050205@aule.net |
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Thread: | |
Lists: | pgsql-general |
> Are you able to take some 'perf top' during high CPU spike and see
> what's burning CPU there? Though the issue is related to blocking, but
> high CPU spikes may hint some spinning to acquire behavior.
Will do, although hopefully the spikes were only growing pains after the
upgrade.
> If your previous relation size is smaller than after upgrade, that's a
> signal that you do have holes in relation, thus extension can be
> avoided sometimes for new tuples.
The relation between high CPU and page splits is not immediately obvious
to me.
We run with synchronous_commit off, but there does seem to be a peak in
I/O requests around the CPU spikes.
Is a page split by nature a synchronous I/O activity? And do the other
connections wait in some kind of CPU intensive form (like a spinlock?)
Kind regards,
Andomar
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