use a thread local rather than a queue so events are in the right order

activesupport/lib/active_support/notifications/fanout.rb

@@ -107,21 +107,18 @@ def matches?(subscriber_or_name)
         end
 
         class Timed < Evented
-          def initialize(pattern, delegate)
-            @timestack = Queue.new
-            super
-          end
-
           def publish(name, *args)
             @delegate.call name, *args
           end
 
           def start(name, id, payload)
-            @timestack.push Time.now
+            timestack = Thread.current[:_timestack] ||= []
+            timestack.push Time.now
           end
 
           def finish(name, id, payload)
-            started = @timestack.pop
+            timestack = Thread.current[:_timestack]
+            started = timestack.pop
             @delegate.call(name, started, Time.now, id, payload)
           end
         end