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From Pete Houston <...@openstrike.co.uk>
Subject Re: [users@httpd] Help troubleshooting performance issue, after "1000 total children" Apache no longer responds to HTTP requests. Not MaxClients issue?
Date Thu, 03 May 2012 21:52:42 GMT
On Thu, May 03, 2012 at 11:29:52AM -0700, P J wrote:
> Good idea about raising the limit to accommodate the peak as a starting
> point, I've switched it to:
> 
> StartServers     500
> MinSpareServers  1024
> MaxSpareServers 1024
> ServerLimit     3500
> MaxClients      3500
> MaxRequestsPerChild  4000
> 
> Then in the error log I'm seeing:
> 
> [info] server seems busy, (you may need to increase StartServers, or
> Min/MaxSpareServers), spawning 32 children, there are 1003 idle, and 1043
> total children
> 
> How can the "server seems busy" with 1003 idle children? yet it is spawning
> 32 more children? Am I totally missing something obvious here?

You have set MinSpareServers and MaxSpareServers to the same value -
this is not a good idea for what should be obvious reasons.

If you have both a high baseline of traffic together with big spikes,
consider something like 256 for MinSpareServers and 1024 for
MaxSpareServers instead. That gives you a big leeway where the server
won't be spawning or reaping a lot of processes.

Not that this will solve your original problem, of course, but it should
prevent apache going nuts trying to have precisely 1024 spare processes
in the meantime.

Do you have enough RAM for 3500 httpd processes? Depending on the
modules you have loaded I'd expect to allow 4-10MB for each process, so
that might be worth a look.

HTH,

Pete
-- 
Openstrike - improving business through open source
http://www.openstrike.co.uk/ or call 01722 770036 / 07092 020107

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