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From Jeff Trawick <>
Subject Re: [users@httpd] Help me in setting up MaxClients
Date Mon, 25 Jan 2010 14:44:35 GMT
On Mon, Jan 25, 2010 at 8:56 AM, Vikrama Sanjeeva
<> wrote:
> Hello All,
> This is regarding production servers. Recently Apache server hit MaxClient
> settings; resulting in crash of sites. However, sites was back to normal
> after restarting Apache.

The expected symptom is that Apache is unresponsive to additional
requests until some of the child processes finish what they're working

Restarting Apache without increasing MaxClients isn't helpful; if it
is a hard restart it trashes the current connections.

> I read about MaxClient settings and increase it from 200 to 250 (as I read
> somewhere that 256 is a limit).

Run apachectl -V to see the limit; it should be in the tens of thousands.

>                                     Since then sites are working fine. But still
> I see average concurrent request on Apache is 180-200 which sometime goes to
> 220 as well. This is threatening, as we are planning to put more sites live
> on same Apache.
> Therefore, I am considering to increase MaxClient in order to handle
> "at-least" 600 concurrent request.
> I will be grateful if somebody can assist me in setting the right values for
> ServerLimit, MaxClient, MinSpareServers and MaxSpareServers.

(I'm trying to get a public URL for the slides I sent you privately
which offer some advice here.)

>                                                              Also, what
> maximum values I can have for MaxClients (want to know max concurrent users
> Apache can handle.)

That's workload-specific.  Here are some interesting notes from
someone playing with a similar box a few years ago:

The official User-To-User support forum of the Apache HTTP Server Project.
See <URL:> for more info.
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