Unconditionally shuts the TendrilManager down, killing all
        threads and closing all tendrils.

def shutdown(self):
        """
        Unconditionally shuts the TendrilManager down, killing all
        threads and closing all tendrils.
        """

        super(UDPTendrilManager, self).shutdown()

        # Reset the socket and socket event
        self._sock = None
        self._sock_event.clear()