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From "Sage Weaver" <s...@nfusion.com>
Subject RE: [users@httpd] Why the sudden need to raise MaxClients?
Date Mon, 20 Feb 2006 15:27:40 GMT
I am having this exact same problem.  I'm also using standard debian
packages for Apache 2.0.54, and the prefork MPM, except my MaxClients
setting is already set to 512.

The minute I hit 513 apache2 processes (listed in "ps -C apache2", the
server stops responding entirely.  Those processes seem to never close.
The only way to fix it is to reload Apache via "/etc/init.d/apache2
restart"

This is not just happening at normal high-traffic times.  Why is httpd
not recovering from this gracefully?  I would assume that, when using
the prefork MPM, as connections close, the processes would close with
them, and the server would then be able to respond to new requests.  But
those child processes never terminate on their own.  Is this normal for
Apache?  If not, what can I do to correct it? 

-----Original Message-----
From: dan+apache-list@dan.tulsa.ok.us
[mailto:dan+apache-list@dan.tulsa.ok.us] 
Sent: Wednesday, February 08, 2006 12:11 AM
To: users@httpd.apache.org
Subject: [users@httpd] Why the sudden need to raise MaxClients?

We are using Apache 2.0.54 on Debian GNU/Linux (standard Debian
packages). The server had been running for several months with
absolutely no problems. A couple of days ago, Apache started slowing
down, then would eventually stop responding completely. The only way to
fix it was to restart Apache. It got to the point that Apache would only
stay functional for a few seconds at a time. Watching the Apache logs
revealed no unusual activity before the lockup.

I discovered the MaxClients setting, which in Debian defaults to 20 for
the prefork MPM. I raised it to 100, and the problem went away. I
believe the default for this value is normally 256.

What would cause this problem all of the sudden? My first thought was a
DOS attack. Am I on the right track?

--df


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