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From "Shapira, Yoav" <>
Subject RE: Odd Memory Problem
Date Fri, 02 Apr 2004 16:19:55 GMT

As you say, it's unfortunate you can't reproduce this on a test server.
What if you setup a test server and let JMeter pound at it for a few

Is there something in your application, e.g. a user action, that would
trigger an infinite loop or infinite recursion?  That would cause that
behavior you've described.  And it would only take one user doing it one
time, i.e. a very light load, to produce this problem.  You'd have to
carefully scrutinize your code...

Yoav Shapira
Millennium Research Informatics

>-----Original Message-----
>From: Rob Wichterman []
>Sent: Friday, April 02, 2004 11:17 AM
>Subject: Odd Memory Problem
>I have been battling a memory problem for a few months now with no
luck.  I
>have used profilers and everything else you could imagine.  The problem
>we have never been able to duplicate it on the testing servers it only
>happens on production which does not see much load at all (100 users a
>I noticed something very odd yesterday though.  I am using the
>"-XX:+UseConcMarkSweepGC and -Xms512m". I was monitoring the garbage
>collection activity very closely and I was receiving good performance
for 3
>days.  I was seeing one garbage collection about every 5 minutes in the
>Catalina.out.  Then out of nowhere the garbage collection starting
>crazy, about one garbage collection a second, I checked the cpu usage
>was stuck around 60% used.  There were only 2-4 people logged in at a
>The crazy garbage collection went on for a couple of hours before it
>eventually crapped out with "Out of Memory" errors.  It almost seems
like a
>section of the app caused this sudden outburst but there is no way our
>department hasn't went over the same section.  I was hoping some one
>heard of this before.  Below is my environment.
>Apache2.0.47 using mod_jk2
>2 * tomcat4.1.24

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