Clear url helper methods when routes are reloaded

Clear url helper methods when routes are reloaded by removing the
methods explicitly rather than just clearing the module because it
didn't work properly and could be the source of a memory leak.

Closes #8488.

1 files changed, 12 insertions, 6 deletions

diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 8168bd4fcc..a993699e05 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -94,7 +94,12 @@ module ActionDispatch
         attr_reader :routes, :helpers, :module
 
         def initialize
-          clear!
+          @routes = {}
+          @helpers = []
+
+          @module = Module.new do
+            instance_methods.each { |selector| remove_method(selector) }
+          end
         end
 
         def helper_names
@@ -102,12 +107,14 @@ module ActionDispatch
         end
 
         def clear!
+          @helpers.each do |helper|
+            @module.module_eval do
+              remove_possible_method helper
+            end
+          end
+
           @routes = {}
           @helpers = []
-
-          @module ||= Module.new do
-            instance_methods.each { |selector| remove_method(selector) }
-          end
         end
 
         def add(name, route)
@@ -291,7 +298,6 @@ module ActionDispatch
 
       def clear!
         @finalized = false
-        @url_helpers = nil
         named_routes.clear
         set.clear
         formatter.clear