In my GWT code I tend to end up with AsyncCallbacks all over the place so that I can support data which is fetched via RPC in all my widgets. It seems to be a commonplace issue that I forget to call the callback, which can be quite difficult to diagnose. To help with that I create a class which “times out” an AsyncCallback. You wrap your AsyncCallback in this object and then you’ll get an error back if no failure or success comes back in a timely fashion.
Debugging GWT AsyncCallback issues by adding a timeout