Out of Perm space

Question

I'm getting out of perm space in an uncertain condition.
The problem can be reproduce with all those settings:
Tomcat 4.1.27 , J2SDK 1.4.1_02 , SunOS 5.8 sparc.
Tomcat 4.1.27 , J2SDK 1.4.2_01 , Windows 2000 pro.
Tomcat 5.0.16 , J2SDK 1.4.2_01 , Windows 2000 pro.
Tomcat 5.0.16 , J2SDK 1.5.0-beta , Windows 2000 pro.
Resin 3.0.5 , J2SDK 1.4.2_01 , Windows 2000 pro.
oc4j 10g (9.0.4) , J2SDK 1.4.2_01 , Windows 2000 pro.
I've used VisualGC to monitor the Memory used by the JVM.
The problem is hard to reproduce but occur when class contained inside a war file (WEB-INF/lib or WEB-INF/classes) are loaded into a classloader.
Normally when a web application is loaded into an servlet container a new classloader is created and the class from WEB-INF/lib and WEB-INF/classes are loaded into the classloader when needed. When a class is loaded the code and symbols are stored into the permanent space. Normally when the classloader is garbage collected, the perm space are release.
The problem occur for certain web application. When some classes are loaded into the classloader a certain condition prevent the JVM from flagged the classloader as collectable. Those class are not constant. I've used the -verbose JVM option to see the class loaded and found nothing in common between the problematic .war files. This problem leads to an increase of the Perm Space size on each reload of the guilty web application. And this leads to some OutOfMemoryError when the perm space reach 64M (this is the default). Increasing the Perm Space is just a temporary solution since the JVM will have to be shutdown and restarted when the Perm Space is full.
My next step is to try other JVM implementation.
Thanks for any help.

Answer 1

I can't figure out how a class can hold that reference. The problem can be reproduced inside a web application that use sun's web service developper pack. Here's a short description of the application.
I've created a smaller application of the original which is a simple servlet that only have a init() method.
Inside the init method I create a client stub with the scope local to init() method. So at this time the classloader loads a couple of classes inside the classloader related with a client jar that contain stub created with wscompile (a tool from the web sevice developper pack used to create soap client stubs) and jaxrpc-impl.jar.
The problem is not just related to this application it can be reproduce with another app that use struts (a framework for building web presentation).
The problem came up when we use the servlet container with a bigger application that was in development that use sun's soap implementation. After for example ~ 12 reloads (which means unreference the classloader and creating a new one) of the application the JVM start to throw OutOfMemoryError.
If I increase the size of the Perm generation it only push back the problem.