def start
      @connection.connect
      @publisher.broadcast(:online)
      @subscriber.subscribe

      EM.add_periodic_timer(1) { heartbeat }

      at_exit do
        @publisher.broadcast(:offline)
        @sessions.delete_all(@id)
      end
    end
def start
      @connection.connect
      @publisher.broadcast(:online)
      @subscriber.subscribe

      EM.add_periodic_timer(1) { heartbeat }

      at_exit do
        @publisher.broadcast(:offline)
        @sessions.delete_all(@id)
      end
    end
Join this node to the cluster by broadcasting its state to the
 other nodes, subscribing to redis channels, and scheduling periodic
 heartbeat broadcasts. This method must be called after initialize
 or this node will not be a cluster member.