Cache ApplicationSetting in memory and bypass Redis
From our analysis in gitlab-com/gl-infra/production#928 (closed), right now
ApplicationSetting appears to be hitting our Redis cache cluster fairly hard:
- 28% of those packets are 2884 bytes due to loading of
- 37% of those packets are TCP ACKs
It seems about 60% of the network overhead is loading of
ApplicationSetting. We should cache this locally within the Unicorn process.