Mailing-List: contact dev-help@httpd.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@httpd.apache.org
Date: Tue, 1 Apr 2003 15:55:36 -0500
From: Dmitri Tikhonov <dmitri@netilla.com>
To: dev@httpd.apache.org
Subject: MaxMemFree: kilobytes or megabytes?
Message-ID: <20030401205536.GB25443@netilla.com>
Mail-Followup-To: dev@httpd.apache.org
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.4i

I'm seeing some weird things happening with MaxMemFree directive
(http://httpd.apache.org/docs-2.0/mod/mpm_common.html#maxmemfree).  The
docs say that this directive specifies the number of kilobytes after
which the memory is returned back to the system, but I found
evidence to the contrary:

On start-up, the size of my Apache process is 20 MB (so large because of
mod_perl and many preloaded Perl modules).  An output filter allocates
about 7 MB.  When MaxMemFree is set to either 1024 (supposedly 1 MB) or
10, the memory is not freed.  When it is set to 1, 2, or 4, the memory
is freed and the process is back to 20 MB.  When it's set to 5 or 6,
the memory is not freed.

The question is, is it really kilobytes, megabytes, or something else?
The code is quite complex, and I was not able to trace it all the way and
figure out exactly what is going on.

I tested this with 2.0.43 and 2.0.45; the filter uses f->r->pool.

Thanks,

  - Dmitri.