Question

I have a Java EE application running on jboss-5.0.0.GA. The application uses BIRT report tool to generate several reports.

The server has 4 cores of 2.4 Ghz and 8 Gb of ram.

The startup script is using the next options:

 -Xms2g -Xmx2g -XX:MaxPermSize=512m

The application has reached some stability with this configuration, some time ago I had a lot of crashes because of the memory was totally full.

Rigth now, the application is not crashing, but memory is always fully used.
Example of top command:

Mem:   7927100k total,  7874824k used,    52276k free

The java process shows a use of 2.6g, and this is the only application running on this server.

What can I do to ensure an amount of free memory?

What can I do to try to find a memory leak?

Any other suggestion?

TIA

---

Based in answer by mezzie:

If you are using linux, what the
kernel does with the memory is
different with how windows work. In
linux, it will try to use up all the
memory. After it uses everything, it
will then recycle the memory for
further use. This is not a memory
leak. We also have jboss tomcat on our
linux server and we did research on
this issue a while back.

I found more information about this,

https://serverfault.com/questions/9442/why-does-red-hat-linux-report-less-free-memory-on-the-system-than-is-actually-ava

http://lwn.net/Articles/329458/

And well, half memory is cached:

             total       used       free     shared    buffers     cached
Mem:          7741       7690         50          0        143       4469

Answer 1

If you are using linux, what the kernel does with the memory is different with how windows work. In linux, it will try to use up all the memory. After it uses everything, it will then recycle the memory for further use. This is not a memory leak. We also have jboss tomcat on our linux server and we did research on this issue a while back.