Bug 899291 (JBPAPP6-365)

project_key: JBPAPP6

During JNDI lookup naming test, I found that ENCFactory seems to be uselessly synchronized in getObjectInstance method.

The important part, Context compCtx = (Context) classloaderKeyedEncs.get(ctxClassLoader) is synchronized by classloaderKeyedEncs which means that every simple get() call is synchronized leading to thread congestion in cases of concurrent JNDI lookups. It is responsible for roughly 3% of total thread blocking (in a heavy JNDI lookup test).

Example diff using synchronized map via Collections is attached. Here is the original code:

   // ObjectFactory implementation ----------------------------------
   public Object getObjectInstance(Object obj, Name name, Context nameCtx,
      Hashtable environment)
      throws Exception
   {
      Object currentId = encIdStack.get();
      if (currentId != null)
      {
         Context compCtx = encById.get(currentId);
         if (compCtx == null)
         {
            compCtx = createContext(environment);
            encById.put(currentId, compCtx);
         }
         return compCtx;
      }
      // Get naming for this component
      ClassLoader ctxClassLoader = GetTCLAction.getContextClassLoader();
      synchronized (classloaderKeyedEncs)
      {
         Context compCtx = (Context) classloaderKeyedEncs.get(ctxClassLoader);

         /* If this is the first time we see ctxClassLoader first check to see
          if a parent ClassLoader has created an ENC namespace.
         */
         if (compCtx == null)
         {
            ClassLoader loader = ctxClassLoader;
            GetParentAction action = new GetParentAction(ctxClassLoader);
            while( loader != null && loader != topLoader && compCtx == null )
            {
               compCtx = (Context) classloaderKeyedEncs.get(loader);
               loader = action.getParent();
            }
            // If we did not find an ENC create it
            if( compCtx == null )
            {
               compCtx = createContext(environment);
               classloaderKeyedEncs.put(ctxClassLoader, compCtx);
            }
         }
         return compCtx;
      }
   }

http://anonsvn.jboss.org/repos/jbossas/projects/naming/tags/5.0.3.GA/jnpserver/src/main/java/org/jboss/naming/ENCFactory.java