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Date: Thu, 8 Feb 2007 08:31:49 -0500
From: "Perrin Harkins" <pharkins@gmail.com>
To: "John ORourke" <john-modperl@o-rourke.org>
Subject: Re: apache MaxClients and locking up
Cc: "mod_perl List" <modperl@perl.apache.org>
In-Reply-To: <45CAE557.3040703@o-rourke.org>
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References: <45CAE557.3040703@o-rourke.org>

On 2/8/07, John ORourke <john-modperl@o-rourke.org> wrote:
> Occasionally the DB gets a bit bogged down and starts taking a while to
> respond (optimisations are being done at the mo), and after a while in
> the error log I get:
>
> [Wed Feb 07 12:35:53 2007] [error] server reached MaxClients setting,
> consider raising the MaxClients setting
>
> and then a whole heap of nothing - I can't tell if the server is still
> accepting new connections at that point as the server accepts
> connections but does nothing, and the system is heavily loaded but still
> responsive at the command line, and it's not using any swap space on
> disk because I tuned the apache/mysql settings properly.

Apache will accept more connections but they will just get queued.
This is described in the docs for the MaxClients setting.

What makes you think the server is doing nothing?  Maybe it's simply
waiting for slow database results.  Have you tried some logging, or
monitoring the database activity?  Have you tried to recreate this
condition artificially with a load testing tool?

- Perrin