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    ClassLoader behaviour on remote clustering tests

    Flavia Rainone Master

      We are seeing an unexpected class loader behaviour in the remote clustering tests, which is resulting in a RuntimeException thrown by JBoss AOP, when aop is run in classical instrumentation mode.

      The cause of this exception is that JBoss AOP is trying to create a class that has already been created and loaded... JBoss AOP tries to create such a class because the class loader that defined the class is not able of loading the same class, which is totally unexpected.

      Look at the pseudocode below:

      ClassLoader myLoader = ....;
      Class class = myLoader.defineClass(....);
      System.out.println("Same class loader: " + (myLoader == class.getClassLoader()));
      System.out.println("I wanted to use this loader: " + loader);
      System.out.println("I got a class with this loader: " + loadedClass.getClassLoader());
      myLoader.load(class.getName());
      


      The call you can see at the second line is actually made by Javassist, through reflection... the code above is a simplification.

      The result of the code above, when run by JBoss AOP during class generation. is a ClassNotFoundException preceeded by the messages:

      Same class loader: false
      I wanted to use this loader: sun.misc.Launcher$AppClassLoader@1a5ab41
      I got a class with this loader: org.jboss.test.messaging.tools.container.ClassLoaderJMXWrapper@6fa9fc
      


      Since the call defineClass has been made to sun.misc.Launcher$AppClassLoader@1a5ab41, we need this class to be able of loading the class later, instead of throwing a ClassNotFoundException.

      Does anybody know why we are seeing this behaviour?

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