def server_kill_reactors(channel)
      @server.mutex.synchronize do
        (@server.subscribers[channel].dup || []).pmap do |hash|
          reactor = hash[:reactor]
          reactor.websocket.close
          Celluloid::Actor.kill(reactor)
        end
      end
    end
def server_kill_reactors(channel)
      @server.mutex.synchronize do
        (@server.subscribers[channel].dup || []).pmap do |hash|
          reactor = hash[:reactor]
          reactor.websocket.close
          Celluloid::Actor.kill(reactor)
        end
      end
    end
kills all reactors registered on a channel and closes their websocket connection

 @param [String] channel
 @return [void]

 @api public