Curious: Why do queue listeners poll Redis and not use the "Subscribe" function of Redis to listen for newly dispatched jobs?

[travisaustin]

Basically, the title.

I use Horizon, but I believe this pertains to "stock" Laravel queues as well.

Basically, the worker process polls Redis periodically (every 1 second, for example) to find out if there are any jobs available to be processed. Redis has a "subscribe" feature that allows a remote system to connect and be immediately informed of newly-available jobs.

I'm curious: why does Laravel poll Redis and not use the Subscribe function? The Subscribe function seems like it's an exact match for Laravel's use-case, and it seems to me like a more elegant way to do it than to poll.

Again, I'm just curious.

Thanks!

[travisaustin]

I found this StackOverflow that reveals that if you've subcribed in a Redis connection, that connection can't be used for anything else. I wonder if maybe this is whay Laravel doesn't use subscribe.

https://stackoverflow.com/questions/32282136/unable-to-fire-a-laravel-event-from-within-a-laravel-redis-pub-sub-subscriber