Is it a good practice to create a channel for each user in redis message bus

Question

We are using redis message bus and handling messages using a channel. But if our application is deployed in multiple instances then the request and response is passed to all the instances. To avoid this scenario which of the below approach is better?

1. Create a channel for each instance of the application
2. Create a channel for each user

Any suggestions will be highly appreciated

Answer 1

The limiting factor here is the number of subscribers to the same channel. Number of channels can be large as such. So you can choose the granularity accordingly. Read more here:

https://groups.google.com/forum/#!topic/redis-db/R09u__3Jzfk

All the complexity on the end is on the PUBLISH command, that performs
an amount of work that is proportional to:

a) The number of clients receiving the message.
b) The number of clients subscribed to a pattern, even if they'll not
match the message.

This means that if you have N clients subscribed to 100000 different
channels, everything will be super fast.

If you have instead 10000 clients subscribed to the same channel,
PUBLISH commands against this channel will be slow, and take maybe a
few milliseconds (not sure about the actual time taken). Since we have
to send the same message to everybody.

Similar question asked before : How does Redis PubSub subscribe mechanism works?