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Re: Pooling in Core WAS: Need help in performance tuning.

From: Andres Freund <andres(at)anarazel(dot)de>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>,Matthew Wakeling <matthew(at)flymine(dot)org>,pgsql-performance(at)postgresql(dot)org
Subject: Re: Pooling in Core WAS: Need help in performance tuning.
Date: 2010-07-22 21:29:54
Message-ID: 20100722212954.GA16758@anarazel.de (view raw or flat)
Thread:
Lists: pgsql-performance
On Thu, Jul 22, 2010 at 02:33:43PM -0400, Robert Haas wrote:
> On Mon, Jul 12, 2010 at 6:58 AM, Craig Ringer
> <craig(at)postnewspapers(dot)com(dot)au> wrote:
> > On 12/07/10 17:45, Matthew Wakeling wrote:
> >>
> >> I'm surprised. Doesn't apache httpd do this? Does it have to do a whole
> >> load of non-portable stuff? It seems to work on a whole load of platforms.
> >
> > A lot of what Apache HTTPd does is handled via the Apache Portable
> > Runtime (APR). It contains a lot of per-platform handlers for various
> > functionality.
>
> Apache just has all of the worker processes call accept() on the
> socket, and whichever one the OS hands it off to gets the job.
As an inconsequential detail - afaik they keep the os from doing that
by protecting it with a mutex for various reasons (speed - as some
implementations wake up and see theres nothing to do, multiple
sockets, fairness)

> The problem is harder for us because a backend can't switch identities
> once it's been assigned to a database.  I haven't heard an adequate
> explanation of why that couldn't be changed, though.
Possibly it might decrease the performance significantly enough by
reducing the cache locality (syscache, prepared plans)?

Andres

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Subject: Re: Pooling in Core WAS: Need help in performance tuning.
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