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From Zdravko Spoljar <zdravko.spol...@styria-it.hr>
Subject Re: [users@httpd] apache over ServerLimit processes limit
Date Mon, 15 Feb 2010 14:01:47 GMT
On Mon, 2010-02-15 at 07:29 -0500, Jeff Trawick wrote:

<cut>

> 
> Anything that causes child processes to exit during steady state can
> lead to extra child processes *when some requests take a relatively
> long time to finish*.

now, if i understand correctly "active child processes" != "child
processes which are terminating" so relative long lived request hold
additional childs alive, and apache spawns new one above ServerLimits to
server new requests. And there is no directive which will limit number
of apache processes in absolute sense? so only solution would be to use
kernel mechanism for limiting number of processes for apache user.
of course that can lead to "worst case" situation in which i will have
up to 1 per child slow request finishing, and no "fast" traffic served
because there are no available threads. 
right? :-)

> Your very low value for MaxRequestsPerChild is the likely culprit.
> You might have to increase MaxSpareThreads as well since that will
> cause one or more child processes to begin termination when load
> decreases by a moderate amount.

that was in because i wanted relative short time of recycling processes,
to avoid memleaks, but i get short of memory due long live requests :-( 
(that is relatively new problem, as php application works for over year)

to summ:
i should rise MaxRequestsPerChild to 5000 (or more), and have slower
rate of recycling processes? and setup some way to kill off long live
requests (maybe killed by firewall setup or by some mod_qos options). 
also setup max number of processes in kernel (and max process RSS size) 
to stabilize server (as apache cannot take care of itself). 

i would rather have locked/crashed apache (which can be detected&fixed
by cron job) than have unusable system due lack of memory (which i need
to fix myself :)

any way, thanks for precise point to my lack of understanding of
implications of using MaxRequestsPerChild != 0.



fli



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