Move behavior to Server::Base, and flush pubsub

actioncable/lib/action_cable/engine.rb

@@ -70,7 +70,6 @@ module ActionCable
 
         app.reloader.before_class_unload do
           ActionCable.server.restart
-          ActionCable.server.pubsub.shutdown
         end
       end
     end

actioncable/lib/action_cable/server/base.rb

@@ -37,9 +37,13 @@ module ActionCable
         connections.each(&:close)
 
         @mutex.synchronize do
-          worker_pool.halt if @worker_pool
-
+          # Shutdown the worker pool
+          @worker_pool.halt if @worker_pool
           @worker_pool = nil
+
+          # Shutdown the pub/sub adapter
+          @pubsub.shutdown if @pubsub
+          @pubsub = nil
         end
       end