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From Sander Temme <scte...@apache.org>
Subject Re: [users@httpd] ServerLimit and MaxClients
Date Sat, 17 Apr 2010 15:01:30 GMT

On Apr 16, 2010, at 11:40 PM, Brent Clark wrote:

> What is the consequences of an overly increased ServerLimit and MaxClients. 

Your server will run out of memory, and start thrashing memory to disk.  Performance quickly
deteriorates.  

> And to add to this puzzle. What if the number of apache process reach that limit.

The first time this happens, you get an emit in the error log.  Apache will run with that
many children until the parent process decides they are not needed anymore.  

MaxClients is a misnomer: it is the maximum number of worker processes/threads the server
will spin up.  Those workers receive incoming connections from the listener socket(s).  When
the server gets busy, connections will queue in the kernel (see ListenBackLog).  Only when
the kernel runs out of resources (your workers don't empty the hopper fast enough) will your
web server start dropping incoming connections. 

S.

-- 
Sander Temme
sctemme@apache.org
PGP FP: 51B4 8727 466A 0BC3 69F4  B7B8 B2BE BC40 1529 24AF




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