From: | "Henshall, Stuart - WCP" <SHenshall(at)westcountrypublications(dot)co(dot)uk> |
---|---|
To: | 'Markus Wollny' <Markus(dot)Wollny(at)computec(dot)de> |
Cc: | "'pgsql-cygwin(at)postgresql(dot)org'" <pgsql-cygwin(at)postgresql(dot)org> |
Subject: | Re: SMP-support on PostgreSQL/Cygwin |
Date: | 2002-03-07 09:42:58 |
Message-ID: | E2870D8CE1CCD311BAF50008C71EDE8E01F74813@MAIL_EXCHANGE |
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Thread: | |
Lists: | pgsql-cygwin |
Hello,
There is no threading in PostgreSQL, it uses a multi process model
where each connection has a back end process. All the postmaster does is
fork new backends, so unless you are doing a lot of connecting the
postmaster shouldn't be doing much. Therefore a transaction will not use
more than one processor. However it sounds as if you have multiple
connections executing at once, so it may be lock contention or I/O bound.
Increasing shared memory buffers may help.
- Stuart
> -----Original Message-----
> From: Markus Wollny [mailto:Markus(dot)Wollny(at)computec(dot)de]
> Sent: 07 March 2002 08:57
>
> Hello!
>
> I've got PostgreSQL 7.2 running on Cygwin on a four-processor Win2K
> server. Now I sometimes notice processor time being very unevenly
> distributed between processors. When I start I time consuming job, at
> the beginning it shows up quite evenly on all four processors. The
> taskmanager shows 12 process-instances of postgres.exe running. One of
> them however seems to consume quite a lot more processing
> power than the
> others - I assume that this one is the daemon-postmaster, which spawns
> all the other processes. In a later stage of the test-job,
> the processor
> time on three of the processors seems to be falling, whereas on one of
> the four usage remains at a high level. This could indicate that the
> postmaster ist running exclusively on this one processor. Hence my
> question: Is there no multithreading in this configuration which would
> allow for a more evenly distribution of processing time on
> all available
> processors?
>
> Greetings,
>
> Markus
>
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