BUG? References to old WebappClassLoaders never released.

[Thomas Åhlen]

To summarize the problem:

I had a memory leak when using Tomcats manager to reload my application.
Analyzing the situation i found that Singeltons are never GC'd. Why? Looking
deeper there seems to be a problem with old WebappClassLoaders never getting
GC'd and the reason seems to be that there are references to the
WebappClassLoaders that never get removed.

See here for more information:

http://nyx.obidobi.net/~thomas/tomcat/index.html

I have located the problem to:

static Hashtables (clBindings, clNameBindings ) located in class
org.apache.naming.ContextBindings.

The classLoaders are added to these Hashtables by a call from
lifecycleEvent in the class NamingContextListner.java

=============>
NamingContextListner.java, 295

            if (container instanceof Context) {
                // Setting the context in read only mode
                ContextAccessController.setReadOnly(getName());
                try {
                    ContextBindings.bindClassLoader
                        (container, container,
                         ((Container)
container).getLoader().getClassLoader());
                } catch (NamingException e) {
                    log(sm.getString("naming.bindFailed", e));
                }
            }

<============

I think that there should be a call to unbindClassLoader in the following
code

NamingContextListner.java, 325

        } else if (event.getType() == Lifecycle.STOP_EVENT) {

            if (!initialized)
                return;

            // Setting the context in read/write mode
            ContextAccessController.setWritable(getName(), container);

 New line ===>   ContextBindings.unbindClassLoader( container, container );

            ContextAccessController.unsetSecurityToken(getName(),
container);

            namingContext = null;
            envCtx = null;
            compCtx = null;
            initialized = false;

        }
}

Thomas



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