Fine tuning JBOSS 3.2.7 for scalability

[ratang2000]

I'm using JBOSS 3.2.7 and facing crisis on performance with around 300 users.We'll ofcourse we are squeezing out any expensive code, but I wanted to know:
1)How JBOSS/Tomcat could be fine tuned to handle http requests faster?
Any configuration parameters?
2)Do we need to increase thread pool size to some value?How can we decide what thread pool size i would require?
(We have a 1GB RAM,PentiumIV 3.0 ghz linux box)
3)Can we upgrade from 3.2.7 to 4.0+ in case we have alot of gain in performance?
4)Are there known performance issues in 3.2.7?

Please give some notes on above questions to solve the crisis we are having...
Thanks
Prateek

[peterj]

Have you looked at http://wiki.jboss.org/wiki/Wiki.jsp?page=SPECjAppServer2002Tuning? Many of the tuning suggestions given there work on any web application.

There is also http://wiki.jboss.org/wiki/Wiki.jsp?page=JBossASTuningSliming.

Extra memory would help. You might need to set the heap at 1200MB and the young generation at 300MB, but to do that you will need at least 2GB of RAM.

[ratang2000]

Thanks!This will definitely help..
What do you recommend for an App server migration?

---
Prateek.

[peterj]

What do you mean by "App server migration"?

[ratang2000]

-I mean, migrating to a different version of JBOSS App server.
Right now Im using 3.2.7, so will migrating to 4.0+ version help in performance??

-Another quicky, right now we have tomcat with jboss.Would putting any other webserver like Jetty etc help in handling http requests faster?

[peterj]

Significant performance improvements went into JBoss 3.2.6/4.0.2 (those improvements were not in 3.2.5/4.0/4.0.1). 4.0.3SP1 showed minor performance improvements over 4.0.2. So I don't think you will see significant improvements by going from 3.2.7 to 4.0.3SP1 or higher.

We have not run JBoss with Jetty, so I would not know.