1 files changed, 37 insertions, 24 deletions

diff --git a/actioncable/lib/action_cable/server/base.rb b/actioncable/lib/action_cable/server/base.rb
index fe48c112df..419eccd73c 100644
--- a/actioncable/lib/action_cable/server/base.rb
+++ b/actioncable/lib/action_cable/server/base.rb
@@ -1,11 +1,11 @@
-require 'thread'
+require "monitor"
 
 module ActionCable
   module Server
-    # A singleton ActionCable::Server instance is available via ActionCable.server. It's used by the rack process that starts the cable server, but
-    # also by the user to reach the RemoteConnections instead for finding and disconnecting connections across all servers.
+    # A singleton ActionCable::Server instance is available via ActionCable.server. It's used by the Rack process that starts the Action Cable server, but
+    # is also used by the user to reach the RemoteConnections object, which is used for finding and disconnecting connections across all servers.
     #
-    # Also, this is the server instance used for broadcasting. See Broadcasting for details.
+    # Also, this is the server instance used for broadcasting. See Broadcasting for more information.
     class Base
       include ActionCable::Server::Broadcasting
       include ActionCable::Server::Connections
@@ -18,15 +18,14 @@ module ActionCable
       attr_reader :mutex
 
       def initialize
-        @mutex = Mutex.new
-
-        @remote_connections = @stream_event_loop = @worker_pool = @channel_classes = @pubsub = nil
+        @mutex = Monitor.new
+        @remote_connections = @event_loop = @worker_pool = @pubsub = nil
       end
 
-      # Called by rack to setup the server.
+      # Called by Rack to setup the server.
       def call(env)
         setup_heartbeat_timer
-        config.connection_class.new(self, env).process
+        config.connection_class.call.new(self, env).process
       end
 
       # Disconnect all the connections identified by `identifiers` on this server or any others via RemoteConnections.
@@ -34,38 +33,52 @@ module ActionCable
         remote_connections.where(identifiers).disconnect
       end
 
+      def restart
+        connections.each(&:close)
+
+        @mutex.synchronize do
+          # 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
+
       # Gateway to RemoteConnections. See that class for details.
       def remote_connections
         @remote_connections || @mutex.synchronize { @remote_connections ||= RemoteConnections.new(self) }
       end
 
-      def stream_event_loop
-        @stream_event_loop || @mutex.synchronize { @stream_event_loop ||= ActionCable::Connection::StreamEventLoop.new }
+      def event_loop
+        @event_loop || @mutex.synchronize { @event_loop ||= ActionCable::Connection::StreamEventLoop.new }
       end
 
-      # The thread worker pool for handling all the connection work on this server. Default size is set by config.worker_pool_size.
+      # The worker pool is where we run connection callbacks and channel actions. We do as little as possible on the server's main thread.
+      # The worker pool is an executor service that's backed by a pool of threads working from a task queue. The thread pool size maxes out
+      # at 4 worker threads by default. Tune the size yourself with <tt>config.action_cable.worker_pool_size</tt>.
+      #
+      # Using Active Record, Redis, etc within your channel actions means you'll get a separate connection from each thread in the worker pool.
+      # Plan your deployment accordingly: 5 servers each running 5 Puma workers each running an 8-thread worker pool means at least 200 database
+      # connections.
+      #
+      # Also, ensure that your database connection pool size is as least as large as your worker pool size. Otherwise, workers may oversubscribe
+      # the database connection pool and block while they wait for other workers to release their connections. Use a smaller worker pool or a larger
+      # database connection pool instead.
       def worker_pool
         @worker_pool || @mutex.synchronize { @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.
-      def channel_classes
-        @channel_classes || @mutex.synchronize do
-          @channel_classes ||= begin
-            config.channel_paths.each { |channel_path| require channel_path }
-            config.channel_class_names.each_with_object({}) { |name, hash| hash[name] = name.constantize }
-          end
-        end
-      end
-
       # Adapter used for all streams/broadcasting.
       def pubsub
         @pubsub || @mutex.synchronize { @pubsub ||= config.pubsub_adapter.new(self) }
       end
 
-      # All the identifiers applied to the connection class associated with this server.
+      # All of the identifiers applied to the connection class associated with this server.
       def connection_identifiers
-        config.connection_class.identifiers
+        config.connection_class.call.identifiers
       end
     end