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Date: Thu, 22 Dec 2011 18:11:06 +1100
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Subject: Re: Tomcat AJP Thread Spike and System Hang
From: Igor Cicimov <icicimov@gmail.com>
To: Tomcat Users List <users@tomcat.apache.org>
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What module are you using on apache side mod_proxy or mod_jk? Also you
might post the Connector settings from tomcat. Sorry typing from my mobile
just think that info might be useful to some one who can help you more.
 On Dec 22, 2011 10:57 AM, "John Minchuk" <minchuk.john@gmail.com> wrote:

> Quick overview of our setup. Http requests flow from our load balancers, to
> squid proxys, to Apaches, to our Tomcat servers.  We migrated to this setup
> from an Oracle App Server.
>
> Apache: 2.2.3
> Tomcat: 7.0.11.0
> JVM: 1.6.0_22-b04
> Linux: 2.6.18-194.17.1.el5
>
> Our production environment has max threads set at 200, the number of
> threads usually hovers around 150.  About twice a day, at seemingly
> unrelated times we get a sudden spike in the number of ajp threads open.
> Eventually this hits our max of 200.  At this point Tomcat still seems
> responsive, but the number of our httpd processes spikes until Apache locks
> ups.  At this point we have monitoring software that kills and restarts
> Apache.  We then manually restart Tomcat.
>
> Here is a graph of the AJP Threads running.  You can see a sudden jump to
> 200 threads.  The other dips are most likely reloads triggered by our
> configuration management software (puppet).
>
> http://sporkit.com/thread_spike/spike.jpg
>
> Also interesting to note, these threads (all 200) appear to be in the keep
> alive state.
>
> http://sporkit.com/thread_spike/threads.jpg
>
> Our access logs don't indicate a high number of visits, or any one
> particular page that might cause this issue (that I can see).
>
> At this point we are stumped.  Do we spend our time tracking down memory
> leaks?  Is there something we could do to at least mitigate the problem
> over the holidays?  Any input greatly appreciated.
>

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