• Stan Hu's avatar
    Add a memory cache local to the thread to reduce Redis load · 978647c6
    Stan Hu authored
    Loading `ApplicationSetting` from Redis was responsible for at least 50%
    of the CPU load of the Redis cluster on GitLab.com. Since these values
    generally don't change very much, we can load this from the database and
    cache it in memory, skipping Redis altogther. We use
    `ActiveSupport::Cache::MemoryStore` as a drop-in replacement for
    `RedisCacheStore` even though we probably don't need synchronized access
    within `Thread.current`.
    Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/63977