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From Don Hill <>
Subject Re: Tomcat 5.5/HTTPD cluster question
Date Fri, 31 Dec 2010 03:46:39 GMT

Thanks for following up on this. From what I can tell it appears that the
HTTPD server is stalling at MaxClients. This usually happens after some
mailing and the site gets hit really hard with users, upward of 3000 active
sessions being handle by 2 HTTPD servers and 4 Tomcat instances. Since we
are using prefork/mod_jk it seems there could also be some high CPU usage. I
have done extensive profiling from a heap perspective using jstat and jmap.
I think I have the JVM tuned pretty good at this point. The Tomcat severs
also had maxthreads for each JVM set really high like 1000 on the AJP/1.3
connector. I brought each JVM down to 200 max threads.

Currently there are 2 VHOSTS on each machine with one  HTTPD instance. We
are load balancing via a F5 Load balancer. The LB manages load accros all 4
VHOST. Each VHOST uses one worker for to talk to one dedicated tomcat JVM.

Besides doing upgrades to Tomcat/HTTPD servers do you think there are any
configuration issues or can you suggest a better layout for this env. I was
thinking of getting rid of the vhosts and use a balancer config in the
mod_jk.config to manage the load to the Tomcat JVMs. This way the load could
be balanced based on the Tomcat usage and not the VHOST usage as some of the
load could be coming from static content and messing up the LB's balancing

I was also thinking that we should switch to worker mpm instead of the

Anyways any thoughts or suggestions would be great.

On Thu, Dec 30, 2010 at 8:19 PM, Christopher Schultz <> wrote:

> Hash: SHA1
> Don,
> On 12/30/2010 10:41 AM, Don Hill wrote:
> > My mistake, Here are the details. I should have confirmed first before
> > posting but besides the apache version everything else is correct.
> >
> > tomcat
> That's not a version published by Tomcat. More likely, this is a version
> packaged by RHEL. If it's really based upon Tomcat 5.5.2 (a reasonable
> guess), you seriously need to upgrade. If that was a typo and you are
> really running Tomcat 5.5.27, then you could still afford to upgrade to
> 5.5.31 which is the latest.
> You described your environment to a certain extent, but didn't say what
> your goals were: are you experiencing any problems with your setup? Are
> you just looking to streamline things so that you can increase load
> without having to upgrade anything?
> If things are going well, why change anything?
> If you have a specific goal, let us know what it is and maybe we can
> help you with it.
> - -chris
> Version: GnuPG v1.4.10 (MingW32)
> Comment: Using GnuPG with Mozilla -
> 6FcAn2MLml4HETMBlCZU8HyRkUFitZr/
> =9iUp
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