Question

我对Akka TCP IO有奇怪的行为，问题是连接重置，因为来自处理程序或TcpMessage.abort()处理程序的Terminating显式调用。 Peer没有收到Tcp.ConnectionClosed事件。例如：

Handler 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通知远程客户端哪个连接错误关闭？如果我从客户端向服务器发送中止，一切正常。

修改

好的，发现问题的根源，只有在我尝试中止之前发送了Write命令时，Abort命令才能工作。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，如果我创建新客户端，则ErrorClosed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按预期接收的中止。

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();
}};

并记录：

[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：

为了使它更清楚一点，问题是：我如何通知我的远程actor处理程序哪个对等体崩溃，ErrorClosed连接（它在远程端进行）。最后ErrorClosed消息总是被卡住，它不会消失，它只是位于选择器中的某个位置，只有在我执行另一个网络操作（将另一个actor写入或连接到服务器）后才推送到对等端。如果我在中止之前执行Write命令，则只会遇到此行为。此行为与操作系统无关;我试过Windows和Linux机器，结果相同。

Answer 1

我没有找到解决此问题的可靠解决方案，但我做了一些事情来减少总体影响。

不要明确使用RST（包括abort命令）。始终与FIN关闭连接（关闭）。即使出现错误。
如果演员因错误而死亡，则信号连接关闭，因此可以正确关闭连接。
使用异步rep-req数据传输机制传输大量数据（ZMQ）。

也可以实现heartbeat actor，但似乎不是一个好主意，特别是Akka IO选择器自己在TCP套接字上运行心跳？

Akka连接中止

1 个答案: