2 files changed, 11 insertions, 10 deletions
diff --git a/actionpack/lib/action_dispatch/routing/inspector.rb b/actionpack/lib/action_dispatch/routing/inspector.rb
index c18dc94d4f..8d7461ecc3 100644
--- a/actionpack/lib/action_dispatch/routing/inspector.rb
+++ b/actionpack/lib/action_dispatch/routing/inspector.rb
@@ -51,7 +51,7 @@ module ActionDispatch
       end
 
       def internal?
-        path =~ %r{/rails/info.*|^#{Rails.application.config.assets.prefix}}
+        controller =~ %r{\Arails/(info|welcome)} || path =~ %r{\A#{Rails.application.config.assets.prefix}}
       end
 
       def engine?
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 0f95daa790..eb9d4b24f1 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -1,5 +1,6 @@
 require 'journey'
 require 'forwardable'
+require 'thread_safe'
 require 'active_support/core_ext/object/to_query'
 require 'active_support/core_ext/hash/slice'
 require 'active_support/core_ext/module/remove_method'
@@ -20,7 +21,7 @@ module ActionDispatch
         def initialize(options={})
           @defaults = options[:defaults]
           @glob_param = options.delete(:glob)
-          @controllers = {}
+          @controller_class_names = ThreadSafe::Cache.new
         end
 
         def call(env)
@@ -68,13 +69,8 @@ module ActionDispatch
       private
 
         def controller_reference(controller_param)
-          controller_name = "#{controller_param.camelize}Controller"
-
-          unless controller = @controllers[controller_param]
-            controller = @controllers[controller_param] =
-              ActiveSupport::Dependencies.reference(controller_name)
-          end
-          controller.get(controller_name)
+          const_name = @controller_class_names[controller_param] ||= "#{controller_param.camelize}Controller"
+          ActiveSupport::Dependencies.constantize(const_name)
         end
 
         def dispatch(controller, action, env)
@@ -130,6 +126,12 @@ module ActionDispatch
         end
 
         def clear!
+          @helpers.each do |helper|
+            @module.module_eval do
+              remove_possible_method helper
+            end
+          end
+
           @routes.clear
           @helpers.clear
         end
@@ -288,7 +290,6 @@ module ActionDispatch
 
       def clear!
         @finalized = false
-        @url_helpers = nil
         named_routes.clear
         set.clear
         formatter.clear