2 files changed, 26 insertions, 6 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/load_interlock.rb b/actionpack/lib/action_dispatch/middleware/load_interlock.rb
new file mode 100644
index 0000000000..07f498319c
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/load_interlock.rb
@@ -0,0 +1,21 @@
+require 'active_support/dependencies'
+require 'rack/body_proxy'
+
+module ActionDispatch
+  class LoadInterlock
+    def initialize(app)
+      @app = app
+    end
+
+    def call(env)
+      interlock = ActiveSupport::Dependencies.interlock
+      interlock.start_running
+      response = @app.call(env)
+      body = Rack::BodyProxy.new(response[2]) { interlock.done_running }
+      response[2] = body
+      response
+    ensure
+      interlock.done_running unless body
+    end
+  end
+end
diff --git a/actionpack/lib/action_dispatch/middleware/params_parser.rb b/actionpack/lib/action_dispatch/middleware/params_parser.rb
index 3776aa78ed..e2b3b06fd8 100644
--- a/actionpack/lib/action_dispatch/middleware/params_parser.rb
+++ b/actionpack/lib/action_dispatch/middleware/params_parser.rb
@@ -26,20 +26,19 @@ module ActionDispatch
     end
 
     def call(env)
-      if params = parse_formatted_parameters(env)
-        env["action_dispatch.request.request_parameters"] = params
-      end
+      default = env["action_dispatch.request.request_parameters"]
+      env["action_dispatch.request.request_parameters"] = parse_formatted_parameters(env, @parsers, default)
 
       @app.call(env)
     end
 
     private
-      def parse_formatted_parameters(env)
+      def parse_formatted_parameters(env, parsers, default)
         request = Request.new(env)
 
-        return false if request.content_length.zero?
+        return default if request.content_length.zero?
 
-        strategy = @parsers.fetch(request.content_mime_type) { return false }
+        strategy = parsers.fetch(request.content_mime_type) { return default }
 
         strategy.call(request.raw_post)