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Re: pl/pgsql function spikes CPU 100%

From: "Shoaib Mir" <shoaibmir(at)gmail(dot)com>
To: "Jeff Frost" <jeff(at)frostconsultingllc(dot)com>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: pl/pgsql function spikes CPU 100%
Date: 2007-03-16 09:36:07
Message-ID: bf54be870703160236v6792e957kc756aa4189a05914@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-admin
Are the stat collector and autovacuum processes in good shape?

--
Shoaib Mir
EnterpriseDB (www.enterprisedb.com)

On 3/16/07, Jeff Frost <jeff(at)frostconsultingllc(dot)com> wrote:
>
> I've got a client that has a function in a db which had been humming along
> quite nicely on 2xOpteron 275, PG 8.1.5, 8GB of RAM.  Now suddenly many of
> the
> functions in the DB if called will spike the CPU to 100%.  These are
> functions
> that used to finish in 7ms, now run for 20-40 mins.  Interestingly, when
> you
> strace the backend, it doesn't appear to be doing too much...here's some
> sample output:
>
> select(0, NULL, NULL, NULL, {0, 1000})  = 0 (Timeout)
> semop(3932217, 0x7fbfffd150, 1)         = 0
> semop(3932217, 0x7fbfffd150, 1)         = 0
> semop(3932217, 0x7fbfffd150, 1)         = 0
> semop(3932217, 0x7fbfffd150, 1)         = 0
> semop(3932217, 0x7fbfffd150, 1)         = 0
> select(0, NULL, NULL, NULL, {0, 1000})  = 0 (Timeout)
> semop(3997755, 0x7fbfffd170, 1)         = 0
> semop(3932217, 0x7fbfffd150, 1)         = 0
>
> Any chance we've stumbled into some corner case bug?  We actually moved
> the DB
> to a different server thinking perhaps we had gotten to the limit of slow
> hardware, but in fact it happens on the other server as well.
>
> I don't see any ungranted locks in pg_locks, nor are there any other non
> idle
> queries this time of the night.
>
> I'll see if I can share the function code tomorrow when people are awake
> again
> in case we have something especially silly in there.
>
>
> --
> Jeff Frost, Owner       <jeff(at)frostconsultingllc(dot)com>
> Frost Consulting, LLC   http://www.frostconsultingllc.com/
> Phone: 650-780-7908     FAX: 650-649-1954
>
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