def _stop(self):
if self._started.isSet():<EOL><INDENT>self._pool_getter.join()<EOL>self._pool_putter.join()<EOL>for worker in self.pool:<EOL><INDENT>worker.join()<EOL><DEDENT>del self._pool_putter<EOL>del self._pool_getter<EOL>del self.pool<EOL>self._tasks = []<EOL>self._tasks_tracked = {}<EOL>self._stopping.clear()<EOL>self._started.clear()<EOL><DEDENT>
(internal) stops input and output pool queue manager threads.