Start the producer.  This will eventually fire the ``server_start``
        and ``running`` events in sequence, which signify that the incoming
        TCP request socket is running and the workers have been forked,
        respectively.  If ``blocking`` is False, control .

def start(self, blocking=True):
        """Start the producer.  This will eventually fire the ``server_start``
        and ``running`` events in sequence, which signify that the incoming
        TCP request socket is running and the workers have been forked,
        respectively.  If ``blocking`` is False, control ."""
        self.setup_zmq()
        if blocking:
            self.serve()
        else:
            eventlet.spawn(self.serve)
            # ensure that self.serve runs now as calling code will
            # expect start() to have started the server even non-blk
            eventlet.sleep(0)