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From Kevan Miller <>
Subject Re: PCRegistry ClassLoader memory leak
Date Tue, 31 Jul 2007 01:13:58 GMT

I've attached two patches to 
OPENJPA-285. I've tested deploy/undeploy scenarios with the two  
patches. They appear to clear up ClassLoader memory leaks associated  
with deployment/undeployment of applications.

The patch to ImplHelper is straight-forward, IMO. _assignableTypes  
maintains a Map of Class, Map pairs. The Class key is WEAK. The  
assignableTo Maps need to use WEAK keys, also. Otherwise, there is a  
chain of HARD references which will prevent GC of the 'to' Class'  

The PCRegistry change was the subject of earlier discussion. I see no  
mechanism of WeakReferences/Stringified object names that would  
permit the appropriate Garbage Collection of the Meta.pc object (and  
it's associated ClassLoader). Instead, this patch adds a  
PCRegistry.deregister(ClassLoader) method. When a ClassLoader is no  
longer viable, Embedders may use this method to cause PCRegistry to  
remove Meta objects from the _metas Map.

My testing shows that these two patches clear up the ClassLoader  
memory leaks (at least in the scenarios I've tested). Hoping that we  
can get these patches applied...



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