Recommended JBoss and Tomcat memory settings?

[Alexander Yap]

Hi all,

Can someone recommend appropriate JVM memory settings ( -Xms and -Xmx ) to start Tomcat and JBoss for best performance?
Is there some guidelines for choosing these values based on available RAM?

I have a single machine running:
- Sun JDK 1.4.2
- MySQL Max 4.0.11
- JBoss 3.2.2 (just serving EJBs)
- Tomcat 4.1.x (running 5 Web apps, 3 of which connect to EJBs on JBoss)
- 1 Swing application (GUI controller for a chat server)

Machine specs:
CPU: Pentium 4 2.2 GHz
RAM: 1 GB
OS: Mandrake Linux 9.1 + KDE 3.1


Thanks.

 

[Mike]

First off, I recommend from experience to use the Jetty version of
JBoss. Don't assume Tomcat is somehow some sort of 'defacto', Tomcat
code internals are actually quite clumsy. Jetty is smooth and
sensible.

Forget the "-server" argument to the JVM, it'll bring out a fatal flaw
in the garbage collector and you can run into a real (open) bug in
JVM.

Try to run with the incremental garbage collector, works *very* well
for me:

java -Xincgc -jar something.jar

It'll keep memory usage nicely low, and will give memory back to the
system. Great for multi user environments. ISP's are you listening?
Nah, they're all morons.