15 files changed, 47 insertions, 37 deletions
diff --git a/actioncable/README.md b/actioncable/README.md
index 9dfa7e8935..636f9935cf 100644
--- a/actioncable/README.md
+++ b/actioncable/README.md
@@ -438,7 +438,7 @@ messages back and forth over the WebSocket cable connection. This dependency may
 be alleviated in the future, but for the moment that's what it is. So be sure to have
 Redis installed and running.
 
-The Ruby side of things is built on top of [faye-websocket](https://github.com/faye/faye-websocket-ruby) and [celluloid](https://github.com/celluloid/celluloid).
+The Ruby side of things is built on top of [faye-websocket](https://github.com/faye/faye-websocket-ruby) and [concurrent-ruby](https://github.com/ruby-concurrency/concurrent-ruby).
 
 
 ## Deployment
diff --git a/actioncable/actioncable.gemspec b/actioncable/actioncable.gemspec
index 74c21bd24d..a04fc932aa 100644
--- a/actioncable/actioncable.gemspec
+++ b/actioncable/actioncable.gemspec
@@ -23,7 +23,6 @@ Gem::Specification.new do |s|
   s.add_dependency 'coffee-rails',     '~> 4.1.0'
   s.add_dependency 'faye-websocket',   '~> 0.10.0'
   s.add_dependency 'websocket-driver', '~> 0.6.1'
-  s.add_dependency 'celluloid',        '~> 0.17.2'
   s.add_dependency 'em-hiredis',       '~> 0.3.0'
   s.add_dependency 'redis',            '~> 3.0'
 
diff --git a/actioncable/lib/action_cable/channel/periodic_timers.rb b/actioncable/lib/action_cable/channel/periodic_timers.rb
index 25fe8e5e54..7f0fb37afc 100644
--- a/actioncable/lib/action_cable/channel/periodic_timers.rb
+++ b/actioncable/lib/action_cable/channel/periodic_timers.rb
@@ -28,7 +28,7 @@ module ActionCable
         def start_periodic_timers
           self.class.periodic_timers.each do |callback, options|
             active_periodic_timers << EventMachine::PeriodicTimer.new(options[:every]) do
-              connection.worker_pool.async.run_periodic_timer(self, callback)
+              connection.worker_pool.async_run_periodic_timer(self, callback)
             end
           end
         end
diff --git a/actioncable/lib/action_cable/connection/base.rb b/actioncable/lib/action_cable/connection/base.rb
index 977856d656..a8cfdf90f3 100644
--- a/actioncable/lib/action_cable/connection/base.rb
+++ b/actioncable/lib/action_cable/connection/base.rb
@@ -103,7 +103,7 @@ module ActionCable
 
       # Invoke a method on the connection asynchronously through the pool of thread workers.
       def send_async(method, *arguments)
-        worker_pool.async.invoke(self, method, *arguments)
+        worker_pool.async_invoke(self, method, *arguments)
       end
 
       # Return a basic hash of statistics for the connection keyed with `identifier`, `started_at`, and `subscriptions`.
diff --git a/actioncable/lib/action_cable/connection/identification.rb b/actioncable/lib/action_cable/connection/identification.rb
index 2d75ff8d6d..885ff3f102 100644
--- a/actioncable/lib/action_cable/connection/identification.rb
+++ b/actioncable/lib/action_cable/connection/identification.rb
@@ -11,7 +11,7 @@ module ActionCable
       end
 
       class_methods do
-        # Mark a key as being a connection identifier index that can then used to find the specific connection again later.
+        # Mark a key as being a connection identifier index that can then be used to find the specific connection again later.
         # Common identifiers are current_user and current_account, but could be anything really.
         #
         # Note that anything marked as an identifier will automatically create a delegate by the same name on any
diff --git a/actioncable/lib/action_cable/process/logging.rb b/actioncable/lib/action_cable/process/logging.rb
index 72b1a080d1..dce637b3ca 100644
--- a/actioncable/lib/action_cable/process/logging.rb
+++ b/actioncable/lib/action_cable/process/logging.rb
@@ -1,10 +1,7 @@
 require 'action_cable/server'
 require 'eventmachine'
-require 'celluloid'
 
 EM.error_handler do |e|
   puts "Error raised inside the event loop: #{e.message}"
   puts e.backtrace.join("\n")
 end
-
-Celluloid.logger = ActionCable.server.logger
diff --git a/actioncable/lib/action_cable/server/base.rb b/actioncable/lib/action_cable/server/base.rb
index 740e4b301e..3785bbd154 100644
--- a/actioncable/lib/action_cable/server/base.rb
+++ b/actioncable/lib/action_cable/server/base.rb
@@ -1,6 +1,3 @@
-# FIXME: Cargo culted fix from https://github.com/celluloid/celluloid-pool/issues/10
-require 'celluloid/current'
-
 require 'em-hiredis'
 
 module ActionCable
@@ -39,7 +36,7 @@ module ActionCable
 
       # The thread worker pool for handling all the connection work on this server. Default size is set by config.worker_pool_size.
       def worker_pool
-        @worker_pool ||= ActionCable::Server::Worker.pool(size: config.worker_pool_size)
+        @worker_pool ||= ActionCable::Server::Worker.new(max_size: config.worker_pool_size)
       end
 
       # Requires and returns a hash of all the channel class constants keyed by name.
diff --git a/actioncable/lib/action_cable/server/worker.rb b/actioncable/lib/action_cable/server/worker.rb
index e063b2a2e1..3b6c6d44a1 100644
--- a/actioncable/lib/action_cable/server/worker.rb
+++ b/actioncable/lib/action_cable/server/worker.rb
@@ -1,39 +1,68 @@
-require 'celluloid'
 require 'active_support/callbacks'
+require 'active_support/core_ext/module/attribute_accessors_per_thread'
+require 'concurrent'
 
 module ActionCable
   module Server
     # Worker used by Server.send_async to do connection work in threads. Only for internal use.
     class Worker
       include ActiveSupport::Callbacks
-      include Celluloid
 
-      attr_reader :connection
+      thread_mattr_accessor :connection
       define_callbacks :work
       include ActiveRecordConnectionManagement
 
+      def initialize(max_size: 5)
+        @pool = Concurrent::ThreadPoolExecutor.new(
+          min_threads: 1,
+          max_threads: max_size,
+          max_queue: 0,
+        )
+      end
+
+      def async_invoke(receiver, method, *args)
+        @pool.post do
+          invoke(receiver, method, *args)
+        end
+      end
+
       def invoke(receiver, method, *args)
-        @connection = receiver
+        begin
+          self.connection = receiver
 
-        run_callbacks :work do
-          receiver.send method, *args
+          run_callbacks :work do
+            receiver.send method, *args
+          end
+        rescue Exception => e
+          logger.error "There was an exception - #{e.class}(#{e.message})"
+          logger.error e.backtrace.join("\n")
+
+          receiver.handle_exception if receiver.respond_to?(:handle_exception)
+        ensure
+          self.connection = nil
         end
-      rescue Exception => e
-        logger.error "There was an exception - #{e.class}(#{e.message})"
-        logger.error e.backtrace.join("\n")
+      end
 
-        receiver.handle_exception if receiver.respond_to?(:handle_exception)
+      def async_run_periodic_timer(channel, callback)
+        @pool.post do
+          run_periodic_timer(channel, callback)
+        end
       end
 
       def run_periodic_timer(channel, callback)
-        @connection = channel.connection
+        begin
+          self.connection = channel.connection
 
-        run_callbacks :work do
-          callback.respond_to?(:call) ? channel.instance_exec(&callback) : channel.send(callback)
+          run_callbacks :work do
+            callback.respond_to?(:call) ? channel.instance_exec(&callback) : channel.send(callback)
+          end
+        ensure
+          self.connection = nil
         end
       end
 
       private
+
         def logger
           ActionCable.server.logger
         end
diff --git a/actioncable/test/connection/authorization_test.rb b/actioncable/test/connection/authorization_test.rb
index 68668b2835..87d0e79ef3 100644
--- a/actioncable/test/connection/authorization_test.rb
+++ b/actioncable/test/connection/authorization_test.rb
@@ -10,7 +10,6 @@ class ActionCable::Connection::AuthorizationTest < ActionCable::TestCase
     end
 
     def send_async(method, *args)
-      # Bypass Celluloid
       send method, *args
     end
   end
diff --git a/actioncable/test/connection/base_test.rb b/actioncable/test/connection/base_test.rb
index da6041db4a..182562db82 100644
--- a/actioncable/test/connection/base_test.rb
+++ b/actioncable/test/connection/base_test.rb
@@ -14,7 +14,6 @@ class ActionCable::Connection::BaseTest < ActionCable::TestCase
     end
 
     def send_async(method, *args)
-      # Bypass Celluloid
       send method, *args
     end
   end
diff --git a/actioncable/test/connection/cross_site_forgery_test.rb b/actioncable/test/connection/cross_site_forgery_test.rb
index d445e08f2a..a29f65fb97 100644
--- a/actioncable/test/connection/cross_site_forgery_test.rb
+++ b/actioncable/test/connection/cross_site_forgery_test.rb
@@ -6,7 +6,6 @@ class ActionCable::Connection::CrossSiteForgeryTest < ActionCable::TestCase
 
   class Connection < ActionCable::Connection::Base
     def send_async(method, *args)
-      # Bypass Celluloid
       send method, *args
     end
   end
diff --git a/actioncable/test/connection/string_identifier_test.rb b/actioncable/test/connection/string_identifier_test.rb
index ab69df57b3..9d0bda83ef 100644
--- a/actioncable/test/connection/string_identifier_test.rb
+++ b/actioncable/test/connection/string_identifier_test.rb
@@ -10,7 +10,6 @@ class ActionCable::Connection::StringIdentifierTest < ActionCable::TestCase
     end
 
     def send_async(method, *args)
-      # Bypass Celluloid
       send method, *args
     end
   end
diff --git a/actioncable/test/connection/subscriptions_test.rb b/actioncable/test/connection/subscriptions_test.rb
index 4f6760827e..62e41484fe 100644
--- a/actioncable/test/connection/subscriptions_test.rb
+++ b/actioncable/test/connection/subscriptions_test.rb
@@ -5,7 +5,6 @@ class ActionCable::Connection::SubscriptionsTest < ActionCable::TestCase
     attr_reader :websocket
 
     def send_async(method, *args)
-      # Bypass Celluloid
       send method, *args
     end
   end
diff --git a/actioncable/test/test_helper.rb b/actioncable/test/test_helper.rb
index 12dcd98402..325305939f 100644
--- a/actioncable/test/test_helper.rb
+++ b/actioncable/test/test_helper.rb
@@ -14,11 +14,6 @@ require 'rack/mock'
 # Require all the stubs and models
 Dir[File.dirname(__FILE__) + '/stubs/*.rb'].each {|file| require file }
 
-$CELLULOID_DEBUG = false
-$CELLULOID_TEST  = false
-require 'celluloid'
-Celluloid.logger = Logger.new(StringIO.new)
-
 require 'faye/websocket'
 class << Faye::WebSocket
   remove_method :ensure_reactor_running
diff --git a/actioncable/test/worker_test.rb b/actioncable/test/worker_test.rb
index 69c4b6529d..9911a3b98b 100644
--- a/actioncable/test/worker_test.rb
+++ b/actioncable/test/worker_test.rb
@@ -17,8 +17,6 @@ class WorkerTest < ActiveSupport::TestCase
   end
 
   setup do
-    Celluloid.boot
-
     @worker = ActionCable::Server::Worker.new
     @receiver = Receiver.new
   end