Cache Flipper persisted names directly to local memory storage

Now that application settings are no longer dominating network traffic,
we see that the Feature#persisted_names is using a significant amount of
CPU and network bandwidth for Redis. Move this cache into the
thread-local memory storage to reduce Redis overhead.

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/feature.rb b/lib/feature.rb
index cc9c9d44005..22420e95ea2 100644
--- a/lib/feature.rb
+++ b/lib/feature.rb
@@ -34,7 +34,9 @@ class Feature
         begin
           # We saw on GitLab.com, this database request was called 2300
           # times/s. Let's cache it for a minute to avoid that load.
-          Rails.cache.fetch('flipper:persisted_names', expires_in: 1.minute) { FlipperFeature.feature_names }
+          Gitlab::ThreadMemoryCache.cache_backend.fetch('flipper:persisted_names', expires_in: 1.minute) do
+            FlipperFeature.feature_names
+          end
         end
     end