remove global cache

activesupport/lib/active_support/notifications.rb

@@ -135,8 +135,6 @@ module ActiveSupport
   # to log subscribers in a thread. You can use any queue implementation you want.
   #
   module Notifications
-    @instrumenters = Hash.new { |h,k| h[k] = notifier.listening?(k) }
-
     class Registry # :nodoc:
       def self.instance
         Thread.current[name] ||= new
@@ -160,7 +158,7 @@ def publish(name, *args)
       end
 
       def instrument(name, payload = {})
-        if @instrumenters[name]
+        if notifier.listening?(name)
           instrumenter.instrument(name, payload) { yield payload if block_given? }
         else
           yield payload if block_given?
@@ -168,9 +166,7 @@ def instrument(name, payload = {})
       end
 
       def subscribe(*args, &block)
-        notifier.subscribe(*args, &block).tap do
-          @instrumenters.clear
-        end
+        notifier.subscribe(*args, &block)
       end
 
       def subscribed(callback, *args, &block)
@@ -182,7 +178,6 @@ def subscribed(callback, *args, &block)
 
       def unsubscribe(args)
         notifier.unsubscribe(args)
-        @instrumenters.clear
       end
 
       def instrumenter