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POTerminate a hung redis pubsub.listen() thread
 

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  1. POTerminate a hung redis pubsub.listen() thread
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    <p>Related to <a href="https://stackoverflow.com/questions/13654243/recover-from-dropped-connection-in-redis-pub-sub">this question</a> I have the following code which subscribes to a redis pubsub queue and uses the handler provided in __init__ to feed the messages to the class that processes them:</p> <pre><code>from threading import Thread import msgpack class Subscriber(Thread): def __init__(self, redis_connection, channel_name, handler): super(Subscriber, self).__init__(name="Receiver") self.connection = redis_connection self.pubsub = self.connection.pubsub() self.channel_name = channel_name self.handler = handler self.should_die = False def start(self): self.pubsub.subscribe(self.channel_name) super(Subscriber, self).start() def run(self): for msg in self.pubsub.listen(): if self.should_die: return try: data = msg["data"] unpacked = msgpack.unpackb(data) except TypeError: # stop non-msgpacked, invalid, messages breaking stuff # other validation happens in handler continue self.handler(unpacked) def die(self): self.should_die = True </code></pre> <p>In the linked question above, it is noted that <code>pubsub.listen()</code> never returns if the connection is dropped. Therefore, my <code>die()</code> function, while it can be called, will never actually cause the thread to terminate because it is hanging on the call to <code>listen()</code> inside the thread's <code>run()</code>.</p> <p>The accepted answer on the linked question mentions hacking redis-py's connection pool. I really don't want to do this and have a forked version of redis-py (at least until the fix is hopefully accepted into master), but I've had a look at the redis-py code anyway and don't immediately see where this change would be made. </p> <p>Does anyone have an idea how to cleanly solve the hanging redis-py <code>listen()</code> call? </p> <p>What issues will I incur by directly using <code>Thread._Thread__stop</code>?</p>
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