Is non-blocking Redis pubsub possible?

Question

I want to use redis' pubsub to transmit some messages, but don't want be blocked using listen, like the code below:

import redis
rc = redis.Redis()

ps = rc.pubsub()
ps.subscribe(['foo', 'bar'])

rc.publish('foo', 'hello world')

for item in ps.listen():
    if item['type'] == 'message':
        print item['channel']
        print item['data']

The last for section will block. I just want to check if a given channel has data, how can I accomplish this? Is there a check like method?

Answer 1

If you're thinking of non-blocking, asynchronous processing, you're probably using (or should use) asynchronous framework/server.

• if you're using Tornado, there is Tornado-Redis. It's using native Tornado generator calls. Its Websocket demo provides example on how to use it in combination with pub/sub.

• if you're using Twisted, there is txRedis. There you also have pub/sub example.

• it also seems that you can use Redis-py combined with Gevent with no problems using Gevent's monkey patching (gevent.monkey.patch_all()).

UPDATE: It's been 5 years since the original answer, in the mean time Python got native async IO support. There now is AIORedis, an async IO Redis client.