2 files changed, 36 insertions, 4 deletions

diff --git a/actionpack/lib/action_controller/metal/live.rb b/actionpack/lib/action_controller/metal/live.rb
index efeeefda9d..48818cb8e4 100644
--- a/actionpack/lib/action_controller/metal/live.rb
+++ b/actionpack/lib/action_controller/metal/live.rb
@@ -6,8 +6,7 @@ module ActionController
     class Response < ActionDispatch::Response
       class Buffer < ActionDispatch::Response::Buffer # :nodoc:
         def initialize(response)
-          @response = response
-          @buf      = Queue.new
+          super(response, Queue.new)
         end
 
         def write(string)
@@ -59,5 +58,30 @@ module ActionController
         buf
       end
     end
+
+    def process(name)
+      t1 = Thread.current
+      locals = t1.keys.map { |key| [key, t1[key]] }
+
+      # This processes the action in a child thread.  It lets us return the
+      # response code and headers back up the rack stack, and still process
+      # the body in parallel with sending data to the client
+      Thread.new {
+        t2 = Thread.current
+        t2.abort_on_exception = true
+
+        # Since we're processing the view in a different thread, copy the
+        # thread locals from the main thread to the child thread. :'(
+        locals.each { |k,v| t2[k] = v }
+
+        begin
+          super(name)
+        ensure
+          @_response.commit!
+        end
+      }
+
+      @_response.await_commit
+    end
   end
 end
diff --git a/actionpack/lib/action_controller/test_case.rb b/actionpack/lib/action_controller/test_case.rb
index c4c825ba6b..ca1ecc43a1 100644
--- a/actionpack/lib/action_controller/test_case.rb
+++ b/actionpack/lib/action_controller/test_case.rb
@@ -517,8 +517,8 @@ module ActionController
       end
 
       def setup_controller_request_and_response
-        @request          = TestRequest.new
-        @response         = TestResponse.new
+        @request          = build_request
+        @response         = build_response
         @response.request = @request
 
         @controller = nil unless defined? @controller
@@ -539,6 +539,14 @@ module ActionController
         end
       end
 
+      def build_request
+        TestRequest.new
+      end
+
+      def build_response
+        TestResponse.new
+      end
+
       included do
         include ActionController::TemplateAssertions
         include ActionDispatch::Assertions