Akka连接中止

Question

我对Akka有奇怪的行为，问题是连接重置，这是由于TcpMessage.abort()从处理程序或Terminating处理程序中显式调用造成的。对等方没有接收到Tcp.ConnectionClosed事件。示例：

处理程序onReceive

@Override
public void onReceive(Object msg) throws Exception {
    if (msg instanceof Tcp.ConnectionClosed) {
        log.info("Server ConnectionClosed: {}", msg);
        getContext().stop(getSelf());
    } else if (msg instanceof Tcp.Received){
        log.info("Aborting connection");
        getSender().tell(TcpMessage.abort(), getSelf());
    }
}

测试代码

new JavaTestKit(system) {{
     getSystem().actorOf(Props.create(Server.class, getRef()), "Server");
     Tcp.Bound bound = expectMsgClass(Tcp.Bound.class);

     ActorRef client = getSystem().actorOf(
     Props.create(Client.class, bound.localAddress(), getRef()), "Client");
     watch(client);
     expectMsgClass(Tcp.Connected.class);
     client.tell(new Message.Write(), getRef());

     expectTerminated(client);
}};

执行后记录

[INFO] [10/19/2013 22:13:22.730] [actorSystem-akka.actor.default-dispatcher-3] [akka://actorSystem/user/Client] Client Connected
[INFO] [10/19/2013 22:13:22.736] [actorSystem-akka.actor.default-dispatcher-3] [akka://actorSystem/user/Client] Sending Write to Handler
[INFO] [10/19/2013 22:13:22.767] [actorSystem-akka.actor.default-dispatcher-3] [akka://actorSystem/user/Server/$a] Aborting connection
[INFO] [10/19/2013 22:13:22.774] [actorSystem-akka.actor.default-dispatcher-3] [akka://actorSystem/user/Server/$a] Server ConnectionClosed: Aborted

java.lang.AssertionError: assertion failed: timeout (3 seconds) during expectMsg: Terminated Actor[akka://actorSystem/user/Client#423174850]

如果我在处理程序中将TcpMessage.abort()更改为TcpMessage.close()：

[INFO] [10/19/2013 22:17:06.243] [actorSystem-akka.actor.default-dispatcher-4] [akka://actorSystem/user/Client] Client Connected
[INFO] [10/19/2013 22:17:06.249] [actorSystem-akka.actor.default-dispatcher-4] [akka://actorSystem/user/Client] Sending Write to Handler
[INFO] [10/19/2013 22:17:06.278] [actorSystem-akka.actor.default-dispatcher-4] [akka://actorSystem/user/Server/$a] Aborting connection
[INFO] [10/19/2013 22:17:06.288] [actorSystem-akka.actor.default-dispatcher-6] [akka://actorSystem/user/Client] Client ConnectionClosed: PeerClosed
[INFO] [10/19/2013 22:17:06.288] [actorSystem-akka.actor.default-dispatcher-3] [akka://actorSystem/user/Server/$a] Server ConnectionClosed: Closed

服务器处理程序如何向远程客户端发送信号--错误关闭了什么连接？如果我将中止从客户端发送到服务器，一切都可以正常工作。

编辑：

好的，找到了问题的根源，只有在尝试中止之前发送写命令时，中止命令才能正常工作。在客户端和服务器上。现在我需要找出原因。

EDIT2:

似乎中止消息被卡住了，如果我创建了新的客户端，那么就可以到达第一个客户端，并向第二个客户端发送相同的写命令，执行客户端预期接收到的中止。

new JavaTestKit(system) {{
    getSystem().actorOf(Props.create(Server.class, getRef()), "Server");
    Tcp.Bound bound = expectMsgClass(Tcp.Bound.class);

    ActorRef client = getSystem().actorOf(
            Props.create(Client.class, bound.localAddress(), getRef()), "Client");
    watch(client);
    expectMsgClass(Tcp.Connected.class);
    client.tell(new Message.Write(), getRef());
    expectNoMsg();

    ActorRef client2 = getSystem().actorOf(
           Props.create(Client.class, bound.localAddress(), getRef()), "Client2");
    watch(client2);
    expectMsgClass(Tcp.Connected.class);

    expectTerminated(client);

    client2.tell(new Message.Write(), getRef());

    expectTerminated(client2);
    expectNoMsg();
}};

和日志：

[INFO] [10/20/2013 00:48:05.923] [actorSystem-akka.actor.default-dispatcher-4] [akka://actorSystem/user/Client] Client Connected
[INFO] [10/20/2013 00:48:05.929] [actorSystem-akka.actor.default-dispatcher-4] [akka://actorSystem/user/Client] Sending Write to Handler
[INFO] [10/20/2013 00:48:05.959] [actorSystem-akka.actor.default-dispatcher-4] [akka://actorSystem/user/Server/$a] Aborting connection, connection actor: [Actor[akka://actorSystem/system/IO-TCP/selectors/$a/2#1767183113]]
[INFO] [10/20/2013 00:48:05.966] [actorSystem-akka.actor.default-dispatcher-6] [akka://actorSystem/user/Server/$a] Server ConnectionClosed: Aborted
[INFO] [10/20/2013 00:48:08.930] [actorSystem-akka.actor.default-dispatcher-6] [akka://actorSystem/user/Client2] Client Connected
[INFO] [10/20/2013 00:48:08.934] [actorSystem-akka.actor.default-dispatcher-3] [akka://actorSystem/user/Client] Client ConnectionClosed: ErrorClosed(An existing connection was forcibly closed by the remote host)
[INFO] [10/20/2013 00:48:08.936] [actorSystem-akka.actor.default-dispatcher-4] [akka://actorSystem/user/Client2] Sending Write to Handler
[INFO] [10/20/2013 00:48:08.937] [actorSystem-akka.actor.default-dispatcher-4] [akka://actorSystem/user/Server/$b] Aborting connection, connection actor: [Actor[akka://actorSystem/system/IO-TCP/selectors/$a/4#-598138943]]
[INFO] [10/20/2013 00:48:08.938] [actorSystem-akka.actor.default-dispatcher-4] [akka://actorSystem/user/Server/$b] Server ConnectionClosed: Aborted
[INFO] [10/20/2013 00:48:08.938] [actorSystem-akka.actor.default-dispatcher-7] [akka://actorSystem/user/Client2] Client ConnectionClosed: ErrorClosed(An existing connection was forcibly closed by the remote host)

EDIT3:

为了让它更清楚一点，问题是:我如何能够告诉我的远程参与者处理程序什么对等程序崩溃了，并ErrorClosed连接(它在远程端执行)。最后一条ErrorClosed消息总是被卡住，它没有消失，它只是位于选择器的某个位置，只在我执行另一个网络操作后才被推送到对等点(写入或连接另一个参与者到服务器)。只有在中止之前执行Write命令时，才会出现此行为。这种行为与操作系统无关；我在Windows和Linux机器上尝试了同样的结果。

Answer 1

我没有为这个问题找到可靠的解决方案，但我做了很少的事情来最大限度地减少总的影响。

1. 不要显式使用RST (这包括中止命令)。始终与鳍紧密相连(关闭)。即使在出错的情况下。
2. 如果操作人员因错误而死亡，则信号连接关闭，因此可以正确关闭连接。
3. 使用异步req数据传输机制来传输大量数据(ZMQ)。

心跳演员也可以实现，但似乎不是很好的主意，特别是Akka IO选择器在TCP套接字上自己运行心跳？