Tomcat on production server, PermGen and redeploys

Question

It looks like

 MemoryError: PermGen space
 java.lang.OutOfMemoryError: PermGen space

is a common problem. You can Increase the size of your perm space, but after 100 or 200 redeploys it will be full. Tracking ClassLoader memory leaks is nearly impossible.

What are your methods for Tomcat (or another simple servlet container - Jetty?) on production server? Is server restart after each deploy a solution?

Do you use one Tomcat for many applications ?

Maybe I should use many Jetty servers on different ports (or an embedded Jetty) and do undeploy/restart/deploy each time ?

Answer 1

Yes indeed, this is a problem. We're running three web apps on a Tomcat server: No. 1 uses a web application framework, Hibernate and many other JARs, no. 2 uses Hibernate and a few JARs and no. 3 is basically a very simple JSP application.

When we deploy no. 1, we always restart Tomcat. Otherwise a PermGen space error will soon bite us. No. 2 can sometimes be deployed without problem, but since it often changes when no. 1 does as well, a restart is scheduled anyway. No. 3 poses no problem at all and can be deployed as often as needed without problem.

So, yes, we usually restart Tomcat. But we're also looking forward to Tomcat 7, which is supposed to handle many memory / class loader problems that are burried into different third-party JARs and frameworks.

Answer 2

I gave up on using the tomcat manager and now always shutdown tomcat to redeploy.

We run two tomcats on the same server and use apache webserver with mod_proxy_ajp so users can access both apps via the same port 80. This is nice also because the users see the apache Service Unavailable page when the tomcat is down.

Answer 3

You can try adding these Java options:

-XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled