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From "Ashraf Mohamed" <>
Subject CPU Spike Every 10 seconds
Date Wed, 10 Jan 2007 19:04:03 GMT

We are running Tomcat 5.5.9 on Windows 2000 Server. Our test involves
500 plus clients sending periodic jsp requests. 

Performance logs show that the tomcat process spikes up to 50% every 10
seconds even AFTER the test has ended and the clients have stopped
sending requests.

Tomcat logs showed the following two statements:

Every 10 seconds:

16:59:46,599 DEBUG (
[org.apache.catalina.startup.HostConfig::checkResources] - Checking
context[/TUP] redeploy resource D:\Program Files\Tomcat\webapps\TUP

Every 60 seconds:

2007-01-09 16:59:36,532 DEBUG (
[org.apache.catalina.session.ManagerBase::processExpires] - Start expire
sessions StandardManager at 1168383576532 sessioncount 0
2007-01-09 16:59:36,563 DEBUG (
[org.apache.catalina.session.ManagerBase::processExpires] - End expire
sessions StandardManager processingTime 31 expired sessions: 02007-01-09

I tried turning off autoDeploy. The redeploy log messages went away, but
the cpu remains the same.

I turned on verbose:gc and the GC logs show collection every 90 seconds
or so. So that does not match the cpu spike.

What does Tomcat do that could cause a cpu spike of almost exactly 50%
almost exactly every 10 seconds?

I have spent a couple of days searching the web, tomcat lists and bug
lists without any luck. Appreciate any help anyone can provide. Thanks.


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