Eager load controller and mailer actions

On the first request, ActionController::Base#action_methods computes
and memoized the list of available actions [1]. With this PR we move
this expensive operation into eager load step to reduce response time
of the first request served in production.

This also reduces the memory footprint when running on forking server
like Unicorn.

[1] https://github.com/rails/rails/blob/a3813dce9a0c950a4af7909111fa730a2622b1db/actionpack/lib/abstract_controller/base.rb#L66-L77

1 files changed, 6 insertions, 0 deletions

diff --git a/actionpack/lib/action_controller/railtie.rb b/actionpack/lib/action_controller/railtie.rb
index 1c1cd58732..0d7a230b17 100644
--- a/actionpack/lib/action_controller/railtie.rb
+++ b/actionpack/lib/action_controller/railtie.rb
@@ -77,5 +77,11 @@ module ActionController
         end
       end
     end
+
+    initializer "action_controller.eager_load_actions" do
+      ActiveSupport.on_load(:after_initialize) do
+        ActionController::Metal.descendants.each(&:action_methods) if config.eager_load
+      end
+    end
   end
 end