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From Kees Jan Koster <>
Subject Re: Question on JVM memory in tomcat
Date Sat, 13 Dec 2008 20:26:17 GMT
Dear user080701,

> I am using the tomcat manager to monitor the health of the tomcat  
> server. I found that the session of JVM, it shown the following  
> information:
> Free memory: 38.13 MB Total memory: 111.18 MB Max memory: 1365.37 MB

As David pointed out, this is probably measured against the committed  
memory, not the max memory.

I just wrote a small post about memory leaks

  In that post I also talk about the difference between maximum memory  
and committed memory.

> Is my tomcat in good condition or not?
> It seems that the free memory is only 38.13MB?
> I have added the following lines in my
> export JAVA_HOME=/opt/jdk
> export JAVA_OPTS=-Xmx1536m
> export CATALINA_HOME=/opt/tomcat
> How to know whether my tomcat can use the memory or not?

You need some form of monitoring that plots max, committed and used  
memory over time, rather than give you samples in numeric format.

You could hook your Tomcat up to Java-monitor. Java-monitor tracks you  
memory usage over two days, so you can see how the memory usage  
develops over time. The graphs in the post are made with Java-monitor.

To use Java-monitor just register on the Java-monitor forum and  
download the probe once you are logged in.
Kees Jan

The secret of success lies in the stability of the goal. -- Benjamin  

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