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From Chris Nokleberg <>
Subject Re: [jira] Commented: (GERONIMO-1062) OpenEJB client leaks memory on each JNDI lookup. Get OutOfMemoryException after a few thousand lookups
Date Fri, 21 Oct 2005 18:07:05 GMT
On Thu, 20 Oct 2005 15:08:05 -0700, David Jencks wrote:
> I spent a couple minutes looking at cglib source code and it looked to  
> me as if they were making some effort to cache enhanced classes.  I  
> would start by trying to figure out why this isn't working for us.   
> AbstractClassGenerator.create(Object key) line 199 looks like it's key.

CGLIB uses a key constructed of all the arguments passed to Enhancer that
could affect the bytecode of the generated class.

This is the code in org.openejb.client.CgLibProxyFactory:

    private Enhancer getEnhancer(Class superClass, Class[] interfaces) {
        Enhancer enhancer;
        enhancer = new Enhancer();
        enhancer.setCallbackFilter(new NoOverrideCallbackFilter(superClass));
        enhancer.setCallbackTypes(new Class[]{NoOp.class, MethodInterceptor.class});
        return enhancer;

The NoOverrideCallbackFilter class does not implement equals/hashCode, so
using a new instance of it for each Enhancer will force generation of a
new class. Because superClass is already part of the key (via
setSuperclass) even something this simple should work:

    public int hashCode() { return 0; }
    public boolean equals(Object o) { return true; }

The memory fixes that Dain alluded to were eliminating some unintentional
references to old classloaders that would prevent them from getting
GC'ed. I don't think they would affect Geronimo but I recommend upgrading


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