How are you importing JoinableQueue? You'll see this error if you import it from multiprocessing.queues instead of directly from multiprocessing. This is because multiprocessing.JoinableQueue is now a function:


    def JoinableQueue(self, maxsize=0):
        '''Returns a queue object'''
        from .queues import JoinableQueue
        return JoinableQueue(maxsize, ctx=self.get_context())

It provides the required context argument for you. Make sure your application is doing "from multiprocessing import JoinableQueue", rather than "from multiprocessing.queues import JoinableQueue".