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From "Jesse Klaasse" <>
Subject Tomcat 100% CPU usage after moving from Java 5 to 6
Date Mon, 25 Jan 2010 11:08:32 GMT
I am running a production environment for a website (over half a million
hits per day), using Tomcat 5.5.20 (I'm stuck to that version due to
support restrictions) behind IIS 6 using JK connector 1.2.28,
tcnative-1.dll (1.1.19) on Windows Server 2003 R2 Enterprise x64 SP2
(with 16 GB RAM). Until last week, I have been using Sun Java 5. Last
week I have upgraded the JDK to Sun Java 6.
The system uses a MS SQL Server 2005 database, which resides on another
That's when things went wrong. At first, all seemed fine (average CPU
usage seems lower than when using Java 5), but after an hour or so (30
minutes - 1,5 hour max) after a Tomcat restart, Tomcat's CPU usage jumps
to 100% (average CPU usage using Java 5 is around 30-40%, peaks around
60%). I can't really figure out what is causing this. I have retried
about 6 restarts (including a complete system reboot), but without any
success. When I move back to Java 5, the problems are gone.
My Tomcat Java arguments:
-Dcatalina.base=D:\tomcat -Dcatalina.home=D:\tomcat
ctory -XX:MaxPermSize=512m
-Xloggc:D:\logs\gc\tomcat-gc.log -XX:+PrintGCDetails -XX:+UseParNewGC
-XX:+UseConcMarkSweepGC -XX:+UseTLAB -XX:+CMSClassUnloadingEnabled
-XX:+CMSPermGenSweepingEnabled -Xms4096m -Xmx10240m
Some further information which could be important:
- I have tried to reproduce the problems on my development environment
(using jMeter for generating server load), but without success;
- I have created some thread dumps during the 100% CPU periods (attached
as a zip file);
I would really like to make the move to Java 6, since Java 5's is EOL.
Any ideas, anyone?

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