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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 more information.

Methods
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Included Modules
Attributes
[R] mutex
Class Public methods
logger()
# File actioncable/lib/action_cable/server/base.rb, line 16
def self.logger; config.logger; end
new()
# File actioncable/lib/action_cable/server/base.rb, line 21
def initialize
  @mutex = Monitor.new
  @remote_connections = @event_loop = @worker_pool = @pubsub = nil
end
Instance Public methods
call(env)

Called by Rack to setup the server.

# File actioncable/lib/action_cable/server/base.rb, line 27
def call(env)
  setup_heartbeat_timer
  config.connection_class.call.new(self, env).process
end
connection_identifiers()

All of the identifiers applied to the connection class associated with this server.

# File actioncable/lib/action_cable/server/base.rb, line 81
def connection_identifiers
  config.connection_class.call.identifiers
end
disconnect(identifiers)

Disconnect all the connections identified by identifiers on this server or any others via RemoteConnections.

# File actioncable/lib/action_cable/server/base.rb, line 33
def disconnect(identifiers)
  remote_connections.where(identifiers).disconnect
end
event_loop()
# File actioncable/lib/action_cable/server/base.rb, line 56
def event_loop
  @event_loop || @mutex.synchronize { @event_loop ||= ActionCable::Connection::StreamEventLoop.new }
end
pubsub()

Adapter used for all streams/broadcasting.

# File actioncable/lib/action_cable/server/base.rb, line 76
def pubsub
  @pubsub || @mutex.synchronize { @pubsub ||= config.pubsub_adapter.new(self) }
end
remote_connections()

Gateway to RemoteConnections. See that class for details.

# File actioncable/lib/action_cable/server/base.rb, line 52
def remote_connections
  @remote_connections || @mutex.synchronize { @remote_connections ||= RemoteConnections.new(self) }
end
restart()
# File actioncable/lib/action_cable/server/base.rb, line 37
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
worker_pool()

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 config.action_cable.worker_pool_size.

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.

# File actioncable/lib/action_cable/server/base.rb, line 71
def worker_pool
  @worker_pool || @mutex.synchronize { @worker_pool ||= ActionCable::Server::Worker.new(max_size: config.worker_pool_size) }
end