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From "Jason Boehle" <jboe...@actuate.com>
Subject RE: problem with high cpu usage on JMeter client
Date Wed, 30 May 2007 21:22:38 GMT
Oops, sent this to the wrong Apache list!  Sorry for the spam.

-----Original Message-----
From: Jason Boehle [mailto:jboehle@actuate.com] 
Sent: Wednesday, May 30, 2007 4:01 PM
To: derby-user@db.apache.org
Subject: problem with high cpu usage on JMeter client

I am trying to load test our web app that talks to a backend server
application we have.  The JMeter test plan is attached.  JMeter 2.2 is
running on a dual-core 3GHz Pentium D, Windows Vista, Sun Java 1.6.0_01,
4GB RAM.

What happens is that the test starts out fine, but about 20 seconds into
it, the JMeter client machine's CPU usage starts to creep up, and
eventually levels off at 50% (pegging one of the CPUs in the dual-core
system), while the CPU usage on the web and server machines steadily
drops off and so does the test throughput.  This is with 5 threads in my
JMeter thread pool.

It smells to me like the JMeter process hits a point where it has filled
up the heap with objects and so the garbage collector thread has to run
constantly (thus the full utilization of one of the processors on my
dual-core box) to free up space for the new objects JMeter keeps
creating.

I have a similar JMeter test that uses the SOAP sampler to issue
requests against our backend server application directly, and it does
not exhibit this problem.  I use the same Switch Controller logic in my
SOAP test, so I don't believe the problem is with it.  It would seem to
me the problem is related to the HTTP samplers and/or HTTP Cookie
Manager used in this particular test.

I have tried moving the Cookie Manager around to different spots in the
tree.
I have tried replacing the variables in my HTTP request samplers with
hardcoded values.
I have tried both types of HTTP request samplers.
I have tried removing the HTTP Request Defaults configuration element.
I have tried Keep-Alive and no Keep-Alive.
I have tried removing my Runtime Controller and setting the Thread Group
to run 1000 times instead.
I have tried setting the HTTP Cookie Manager to clear cookies on each
iteration.
So far I have not been able to eliminate or identify the problem with my
JMeter test.

What should be my next step in troubleshooting this problem?  What
additional information can I provide to help?

Thanks!

Jason Boehle
jboehle@actuate.com

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