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From "Shapira, Yoav" <Yoav.Shap...@mpi.com>
Subject RE: Memory Allocation
Date Wed, 22 Jan 2003 14:29:25 GMT
Howdy,
Whoa there ;)  Be very careful about some things:

- The amount of memory tomcat takes on startup is variable.  This
changes with tomcat version, OS version, JDK version, configured webapps
and their listeners / filters / load-on-startup servlets, any
Loggers/Valves/Realms configured for tomcat in server.xml, etc.  As you
can see this is many variables.

- Using a debugger such as JProbe or OptimizeIt may inflate the memory
usage of a system by a factor of 10 or more.

- What the other guy said about the default heap set at 64MB -- the
default heap MAXIMUM is set as 64MB.  The default minimum is very small,
again depending on JDK version and flags used.  

For an illustration, try the following:
- Set -Xmx10m in your JAVA_OPTS to allow only 10MB on the heap.
- Start tomcat without a debugger.  You shouldn't have a problem.
- Try to start tomcat with a debugger.  See what happens ;)

Yoav Shapira
Millennium ChemInformatics


>-----Original Message-----
>From: Hari Venkatesan [mailto:hvenkatesan@pfgc.com]
>Sent: Tuesday, January 21, 2003 4:21 PM
>To: tomcat-user@jakarta.apache.org
>Subject: Memory Allocation
>
>Tomcat when starting uses 60M memory in heap. Why is that it is using
so
>much memory in heap. I found this by running jprobe memory debugger. I
>have just one application in the context of server.xml file and don't
>think the entire application gets loaded into memory. After doing a
full
>garbage collection, the heap memory comes down to 11M. Is something
>going wrong or is it the way tomcat behaves?
>
>Hari

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