From: Jim C. Nasby <jnasby@pervasive.com>
To: Ameet Kini <akini@cs.wisc.edu>
Cc: pgsql-performance@postgresql.org
Subject: Re: Lots of postmaster processes (fwd)
Date: Fri, 16 Dec 2005 15:56:52 -0600
Message-ID: <20051216215652.GS53809@pervasive.com> (raw)
In-Reply-To: <Pine.LNX.4.58.0512131124550.1030@karadi.cs.wisc.edu>
References: <Pine.LNX.4.58.0512131124550.1030@karadi.cs.wisc.edu>
Dunno if this has gotten a reply elsewhere, but during a checkpoint the
database can become quite busy. If that happens and performance slows
down, other queries will slow down as well. If you have an app where a
a high rate of incomming requests (like a busy website), existing
backends won't be able to keep up with demand, so incomming connections
will end up spawning more connections to the database.
On Tue, Dec 13, 2005 at 11:25:40AM -0600, Ameet Kini wrote:
>
>
> Resending it here as it may be more relevant here...
> Ameet
>
> ---------- Forwarded message ----------
> Date: Tue, 13 Dec 2005 11:24:26 -0600 (CST)
> From: Ameet Kini <akini@cs.wisc.edu>
> To: pgsql-admin@postgresql.org
> Subject: Lots of postmaster processes
>
>
>
> In our installation of the postgres 7.4.7, we are seeing a lot of the
> following postmaster processes (around 50) being spawned by the initial
> postmaster process once in a while:
>
> postgres 3977 1 1 Nov03 ? 15:11:38
> /s/postgresql-7.4.7/bin/postmaster -D /scratch.1/postgres/condor-db-7.4.7
>
> ......
>
> postgres 31985 3977 0 10:08 ? 00:00:00
> /s/postgresql-7.4.7/bin/postmaster -D /scratch.1/postgres/condor-db-7.4.7
>
> postgres 31986 3977 0 10:08 ? 00:00:00
> /s/postgresql-7.4.7/bin/postmaster -D /scratch.1/postgres/condor-db-7.4.7
>
> postgres 31987 3977 0 10:08 ? 00:00:00
> /s/postgresql-7.4.7/bin/postmaster -D /scratch.1/postgres/condor-db-7.4.7
>
> postgres 31988 3977 0 10:08 ? 00:00:00
> /s/postgresql-7.4.7/bin/postmaster -D /scratch.1/postgres/condor-db-7.4.7
>
> ......
>
>
> At the same time when these processes being spawned, sometimes there is
> also the checkpoint subprocess. I am not sure if that is related. The
> document doesn't provide any information. The other activity going on at
> the same time is a 'COPY' statement from a client application.
>
> These extra processes put a considerable load on the machine and cause it
> to hang up.
>
> Thanks,
> Ameet
>
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--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com, akini@cs.wisc.edu
Subject: Re: Lots of postmaster processes (fwd)
In-Reply-To: <20051216215652.GS53809@pervasive.com>
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