Faster expiration of application settings
Right now there is a per-thread memory cache for application settings to reduce load from Redis and PostgreSQL. It is expired locally every 60 seconds.
This has a problem where it may take up to 60 seconds to see changes.
We may need to consider a scheme where we check a small key in Redis that holds the version number of the latest application settings. If it is not the latest, we either read from another Redis key or read from the database.