protected void cleanupDefunctDisplays()
   {
      List<IWorkbenchProvider> workbenchProviders = Activator.getDefault().getServices(IWorkbenchProvider.class);
      final List<IWorkbench> pendingResponse = new CopyOnWriteArrayList<IWorkbench>(); 
      CountDownLatch countDownLatch = new CountDownLatch(workbenchProviders.size());
      
      for (IWorkbenchProvider wbProvider: workbenchProviders) {
         final IWorkbench wb = wbProvider.getWorkbench();
         Display display = wb.getDisplay();
         if (display == null || display.isDisposed()) {
            // display is already dead, call countDown to be sure we don't wait uneccesarily and move along
            countDownLatch.countDown();
            continue;
         }
         // mark as pending response
         pendingResponse.add(wb);
         display.asyncExec(new Runnable()
         {
            public void run()
            {
               // it only runs this when the client is still alive, so remove from the list
               pendingResponse.remove(wb);
            }
         });
      }
      // wait at most 5 seconds because there is a polling refresh at that interval
      try {
         countDownLatch.await(5, TimeUnit.SECONDS);
      } catch (InterruptedException e) {
         // Thread was interrupted, just bail
         e.printStackTrace();
         return;
      }
      for (final IWorkbench wb: pendingResponse) {
         // this display is not responding, so kill it
         // TODO is this the best way to close? call display.dispose()? use IWorkbenchConfigurer.emergencyClose()?
         try {
            Display display = wb.getDisplay();
            if (display != null && !display.isDisposed() && !wb.isClosing()) {
               IDisplayAdapter displayAdapter = (IDisplayAdapter)display.getAdapter(IDisplayAdapter.class);
               // HACK Synchronizer doesn't release locks on dispose, see bug 328347
               while(displayAdapter.getAsyncRunnablesCount() > 0) {
                  try {
                     Method method = IDisplayAdapter.class.getMethod("runAsyncRunnables");
                     method.setAccessible(true);
                     method.invoke(displayAdapter);
                  } catch (Exception e) {
                     e.printStackTrace();
                  }
               }
               // kill the session which should cleanup everything else
               displayAdapter.getSession().getHttpSession().invalidate();
            }
         } catch (Exception e) {
            e.printStackTrace();
         }
      }
      
   }