Subscribe only to known room to reduce redis traffic

[realturner]

Hi,

We have a project using multiple server instance with lots of users attempting to send messages to each other, making lots of rooms of small amount of members per room. By examining the source code, I think replacing redis command psubscribe to subscribe of specific rooms can help reduce traffic that some server instance may not have such room to be processed.

From our experiment running on production environment, it helped us reduce 50% of redis outgoing bandwidth. If this idea seems making sense to you, please consider merging.

Best,
Tso-Shuo Tsao

[darrachequesne]

Hi! Thanks for the pull request.

Actually, it was implemented like that in the past, see:

• Why add subscription for each room? #102
• Make use of redis pub-sub for improved performance #46

[realturner]

Hi! Thanks for your reply.

I didn't know that designing adapter with pub/sub requires many considerations and had already been discussed before. That's quite exciting for me that I am not the only one encountering similar issue, but also makes me being sorry for not investigating enough before sending PR. 😅 .

I haven't yet going through all details you mentioned, but I do see your latest comments in #207. I believe there is a reason for the removal of withChannelMultiplexing option so we should better not to merge this.

I'll close this PR.

Best,
Tso-Shuo Tsao