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From Simon Pabst <>
Subject RE: Tomcat Load Balancing / Session Clustering - Tests
Date Thu, 10 Jul 2003 17:02:36 GMT
If you are using a webserver stresstest tool like siege 
( be sure to have a delay (5secs or more) 
between the requests.
Because otherwise if the requests come too fast, the load balancing round 
robin will get screwed up (i think mod_jk(2)'s worker stats aren't updated 
quick enough),
like this:

Siege in benchmark mode (--benchmark on cmdline):
20 or more requests go to first tomcat
20 or more to second
20 or more to third
and so on...

Siege with delay of 5 secs (--delay=5):
1-2 requests to first tomcat
1-2 to second

And use something without a session for testing, like an image (or use 

At 12:15 10.07.2003 -0400, you wrote:
>thanks Ben!
>-----Original Message-----
>From: Ben Ricker []
>Sent: Thursday, July 10, 2003 11:35 AM
>To: Tomcat Users List
>Subject: Re: Tomcat Load Balancing / Session Clustering - Tests
>Well, load testing on the Apache end would be the way to go for
>scalability testing. You can monitor the network connections to the
>Tomcat instances (use of netstat does well here; grep for the number of
>connections to each port every N seconds or minutes, etc.).
>To test the session stuff, try shutting down instances as you are
>running through the app. Can you access each Tomcat instance
>individually? The best way is to use each Tomcat's web server and to
>access it on the port. Then, shut down that Tomcat and access another
>Tomcat by its port. If your session continues unaffected, you are good
>to go.
>If you have a REALLY good load tester that can capture page data (i.e.,
>return codes and pages from the web server), you could randomly shutdown
>Tomcat instances while load testing to see how that affects the ouput.
>Ben Ricker
>On Thu, 2003-07-10 at 09:52, Weissman, Alan wrote:
> > Hey everyone,
> >
> > I've set up a few Tomcat instances in a cluster and would like to test the
> > scalability of the cluster as well as make sure the session clustering is
> > working.  Testing scalability is easy and I have load balncing software,
> > whats the best way to make sure that sessions are clustering as expected?
> >
> > Thanks,
> >
> > Alan Weissman
> > Systems Engineer
> > Concord Financial Technologies
> >
> >
> >
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