Java profiling Permgen: how to unload enum inside java class

Question

I'm in a place where repeated deploy-undeploy actions of the same war-file on server (tomcat) is leading to PermGen OutOfMemoryError. My goal is to make sure that I unload all classes when the war is undeployed.

Here is a class I have:

public class ClassA {
//static variables & methods
//instance variables & methods

    private EnumInsideClassA myState = EnumInsideClassA.VALUE1;

    private enum EnumInsideClassA
    {
        VALUE1,
        VALUE2
    }
}

When I cleared all the references of ClassA, I could not see ClassA and it was unloaded when war was un-deployed. However, I still see the enum references and ClassA$EnumInsideClassA is not unloaded.

There is no getter for 'myState' instance variable and it just going to be used with ClassA

Any help is appreciated

Answer 1

However, I still see the enum references and ClassA$EnumInsideClassA is not unloaded.

If you can see the enum references, you should be able to see where they are. Now there will be some enum references accessible via a hidden static field of the enum class, but these should be circular references and shouldn't cause the enum to remain reachable. See if there are enum references somewhere else.