Currently, the celery worker executing workflows / chatflows uses redis pubsub to publish events to api.
(See \_topic\_msg\_generator and \_publish\_streaming\_response)
The current implementation uses the default redis client.
For large scale deployment, we need to use a dedicated redis cluster to ensure performance.
To achieve this, you should:
1. introduce a dedicated configuration class to control
the redis address used for pubsub. (Ideally, there should only be one configuration item such as `pubsub_redis_url`, and its default value should be the original redis confugration.)
2. Add an option to switch between pubsub and sharded pubsub. When shared pubsub is specified, the ShardedRedisBroadcastChannel should be used instead.
COmplete the task above, add some unit tests.
