Hey, I realize that the point of deferreds is to have process/network intensive tasks work on in their own thread and send the results to callback function in the main thread, but is there away to have a deferred process it's callback in a non-main thread? I'm sure someone will want to know why, and maybe solving my meta-problem would show me the errors in my ways in wanting to warp the purpose of the mighty deferred. Async is great, but I'm slowly replacing some code that uses xmlrpc (blocking) with prospect broker objects (returns deferred, hence non-blocking). What I'm trying to hack is a method to make a non-blocking call in the main thread blocking until the deferred returns a result, hence emulating the blocking nature of xmlrpc. This dependency is something I would like to phase out, but certain things need it, so work with me eh? My hack is to simply use a threading.Event to wait for the callback to be called in a non-waiting thread, save the value and do the let the main thread return the result. Of course this doesn't work when callbacks run in the main thread because the main thread is blocked. #Bits of hack code: class Block def waitFor(self, function, *args, **kwargs): if not hasattr(self,'async_done'): self.async_done = threading.Event() self.result = None #ceate a thread to wait for callback. threads.deferToThread(function, *args, **kwargs).addCallback(self._cbWait).addErrback(self._ebWait) #block on results of thread to be set self.async_done.wait() self.async_done.clear() return self.result #This is never called, because main thread is blocked def _cbWait(self, deferred): #expect original function to return a deferred deferred.addBoth(self._cbValue) def _ebWait(self, reason): print "ERROR in getting remote function: ",reason def _cbValue(self, v): self.result = v self.async_done.set() Any ideas O masters of the twisted? Gabe Rudy