Akka TCP Comand Failed - scala

Question

I'm writing a client and server applications using Akka Tcp and I'm having a issue with a high throughput.
When I write too many messages on the client side, I'm having too many CommandFailed messages and I can't figure out why...
Here's my server:
class Server(listener: ActorRef) extends Actor {
import Tcp._
import context.system
IO(Tcp) ! Bind(self, new InetSocketAddress("localhost", 9090))
def receive = {
case CommandFailed(_: Bind) => {
println("command failed error")
context stop self
}
case c#Tcp.Connected(remote, local) =>
listener ! GatlingConnected(c.remoteAddress.toString)
println("Connected: " + c.remoteAddress)
val handler = context.actorOf(Props(classOf[ServerHandler], listener, c.remoteAddress.toString))
val connection = sender
connection ! Register(handler)
}
}
class ServerHandler(listener: ActorRef, remote: String) extends Actor {
import Tcp._
override def receive: Receive = {
case Received(data) => listener ! data.utf8String
case PeerClosed => {
listener ! Finished(remote)
context stop self
}
}
}
Message and Finished are just case classes that I've createad.
Here's the client (where I think its the source of this problem):
private class TCPMessageSender(listener: ActorRef) extends BaseActor {
final val MESSAGE_DELIMITER = "\n"
val buffer = new ListBuffer[Any]
val failedMessages = new ListBuffer[Write]
IO(Tcp) ! Connect(new InetSocketAddress(configuration.data.tcp.host, configuration.data.tcp.port))
override def receive = {
case msg # (_: UserMessage | _: GroupMessage | _: RequestMessage) =>
logger.warn(s"Received message ($msg) before connected. Buffering...")
buffer += msg
case CommandFailed(_: Connect) =>
logger.warn("Can't connect. All messages will be ignored")
listener ! Terminate
context stop self
case c # Connected(remote, local) =>
logger.info("Connected to " + c.remoteAddress)
val connection = sender
connection ! Register(self)
logger.info("Sending previous received messages: " + buffer.size)
buffer.foreach(msg => {
val msgString: String = JsonHelper.toJson(Map[String, Any]("message_type" -> msg.getClass.getSimpleName, "message" -> msg))
connection ! Write(ByteString(msgString + MESSAGE_DELIMITER))
})
buffer.clear
logger.info("Sent")
context become {
case msg # (_: UserMessage | _: GroupMessage | _: RequestMessage) =>
val msgString: String = JsonHelper.toJson(Map[String, Any]("message_type" -> msg.getClass.getSimpleName, "message" -> msg))
logger.trace(s"Sending message: $msgString")
connection ! Write(ByteString(msgString + MESSAGE_DELIMITER))
case CommandFailed(w: Write) =>
logger.error("Command failed. Buffering message...")
failedMessages += w
connection ! ResumeWriting
case CommandFailed(c) => logger.error(s"Command $c failed. I don't know what to do...")
case Received(data) =>
logger.warn(s"I am not supposed to receive this data: $data")
case "close" =>
connection ! Close
case _: ConnectionClosed =>
logger.info("Connection closed")
context stop self
case WritingResumed => {
logger.info("Sending failed messages")
failedMessages.foreach(write => connection ! write)
failedMessages.clear
}
}
}
}
Sometimes I receive a lot of CommandFailed messages and I call ResumeWrite and never receive a WritingResumed (and the connection never closes in this cases). Am I doing something wrong?

Answer 1

I think the problem is that when you register your actor sending the Register message, you also have to set the useResumeWriting parameter to true:
connection ! Register(handler, false, true)
The doc of resumeWriting command states:
When `useResumeWriting` is in effect as was indicated in the [[Tcp.Register]] message
then this command needs to be sent to the connection actor in order to re-enable
writing after a [[Tcp.CommandFailed]] event. All [[Tcp.WriteCommand]] processed by the
connection actor between the first [[Tcp.CommandFailed]] and subsequent reception of
this message will also be rejected with [[Tcp.CommandFailed]].