Tune tcp-backlog for Redis instances with high connection count
https://developer.redis.com/operate/redis-at-scale/talking-to-redis/initial-tuning/#set-tcp-backlog
We default to 511 for our tcp-backlog across all instances. It was pointed out in https://gitlab.slack.com/archives/C04M6HVAY49/p1709702019024719?thread_ts=1709288373.802859&cid=C04M6HVAY49 by @f_santos that we do not set it for redis-pubsub
.
Sources
- gitlab-redis-cluster cookbook defaults - https://gitlab.com/gitlab-cookbooks/gitlab-redis-cluster/-/blob/master/attributes/default.rb
- omnibus-gitlab redis config defaults - https://gitlab.com/gitlab-org/omnibus-gitlab/-/blob/8b1c40c46b75ccc2fbf078165d19df7307a5b2e7/files/gitlab-cookbooks/redis/attributes/attributes.rb#L24
We should do a review of our Redises and adjust tcp-backlog if needed.