设置

我有一台运行4个UDP客户端的主机，每个客户端都有自己的线程（T1，T2，T3和T4）。 T1和T2共享一个名为 socket 的DatagramSocket对象，而T3和T4共享一个名为 socket2 的DatagramSocket对象。

T1和T2正在IP（例如） udpServer1 从UDP服务器发送和接收回声，而T3和T4正在与 udpServer2 进行通信。

问题

我能够同步T1和T2，它们在并行运行线程时共享相同的DatagramSocket和Runnable对象。但是，当尝试运行使用不同DatagramSocket和Runnable对象的T1和T3时，T3总是因SocketTimeoutException而失败，但T1可以发送和接收数据包没有问题。

总结：

并行运行T1和T2（或T3和T4），共享相同的DatagramSocket和Runnable对象 - ＆gt;确定
并行运行T1和T3，每个使用自己的DatagramSocket和Runnable对象 - ＆gt;其中一个的SocketTimeoutException。

问题

为什么T3继续获取SocketTimeoutException，即使它在自己的DatagramSocket上并在自己的线程上运行？我在这里做错了什么？

非常感谢任何帮助。感谢。

测试代码

@Test
public void sendRemoteTest() throws InterruptedException, IOException {
    DatagramSocket socket = new DatagramSocket(9987, InetAddress.getByName(localMachineIp));
    DatagramSocket socket2 = new DatagramSocket(9988, InetAddress.getByName(localMachineIp));
    UdpClientRunnable runnable = new UdpClientRunnable(socket, 1);
    UdpClientRunnable runnable2 = new UdpClientRunnable(socket2, 1);

    Thread t1 = new Thread(runnable);
    t1.setName("T1");
    Thread t2 = new Thread(runnable);
    t2.setName("T2");
    Thread t3 = new Thread(runnable2);
    t3.setName("T3");
    Thread t4 = new Thread(runnable2);
    t4.setName("T4");
    t1.start();
    t2.start();
    t3.start();
    t4.start();
    Thread.sleep(10000);
    t1.join();
    t2.join();
    t3.join();
    t4.join();
}

private byte toByte(int num) {
    return (byte) ((byte) (0xFF) & num);
}

public class UdpClientRunnable implements Runnable {
    private DatagramSocket socket;
    private long delayMillis;
    private byte[] dataToSend;

    public UdpClientRunnable(DatagramSocket socket, long delayMilis) {
       this.socket = socket;
       this.delayMillis = delayMilis;
    }

    @Override
    public synchronized void run() {
       byte[] data1 = new byte[] { toByte(0x01), toByte(0x01), toByte(0x01),
          toByte(0x01), toByte(0x01) };
       byte[] data2 = new byte[] { toByte(0x02), toByte(0x02), toByte(0x02),
          toByte(0x02), toByte(0x02) };
       byte[] data3 = new byte[] { toByte(0x03), toByte(0x03), toByte(0x03),
          toByte(0x03), toByte(0x03) };
       byte[] data4 = new byte[] { toByte(0x04), toByte(0x04), toByte(0x04),
          toByte(0x04), toByte(0x04) };

       String targetIp = "";
       String name = Thread.currentThread().getName();
       if (name.contains("T1")) {
          dataToSend = data1;
          targetIp = udpServer1;
       }
       else if (name.contains("T2")){
          dataToSend = data2;
          targetIp = udpServer1;
       }
       else if (name.contains("T3")) {
          dataToSend = data3;
          targetIp = udpServer2;
       }
       else {
          dataToSend = data4;
          targetIp = udpServer2;
       }
       int count = 0;
       while (count < 250) {
          try {
             sendAndReceive(targetIp, name, count, dataToSend);
             Thread.sleep(delayMillis);
          }
          catch (IOException | InterruptedException e) {
             System.out.println(e + ": " + name + ", iter: " + count);
          }
          finally {
             ++count;
          }
       }
    }

    private synchronized void sendAndReceive(String targetIp, String threadName, int count, byte[] dataToSend) throws IOException, UnknownHostException, SocketException {
        byte[] rcvData = new byte[5];
        DatagramPacket rcvPacket = new DatagramPacket(rcvData, rcvData.length);
        socket.send(new DatagramPacket(dataToSend, 5, InetAddress.getByName(targetIp), 9999));
        socket.setSoTimeout(2000);
        rcvPacket = new DatagramPacket(rcvData, rcvData.length);
        socket.receive(rcvPacket);
        printData(threadName, count, rcvData);
        if (threadName.contains("T1")) {
            Assert.assertArrayEquals(new byte[] { toByte(0x01), toByte(0x01), toByte(0x01),
                toByte(0x01), toByte(0x01) }, rcvData);
        }
        else if (threadName.contains("T2")){
            Assert.assertArrayEquals(new byte[] { toByte(0x02), toByte(0x02), toByte(0x02),
                toByte(0x02), toByte(0x02) }, rcvData);
        }
        else if (threadName.contains("T3")){
            Assert.assertArrayEquals(new byte[] { toByte(0x03), toByte(0x03), toByte(0x03),
                toByte(0x03), toByte(0x03) }, rcvData);
        }
        else if (threadName.contains("T4")){
            Assert.assertArrayEquals(new byte[] { toByte(0x04), toByte(0x04), toByte(0x04),
                toByte(0x04), toByte(0x04) }, rcvData);
        }
    }

    private void printData(String name, int count, byte[] rcvData) {
        String prefix = "";
        for (int i = 0; i < rcvData.length; i++) {
            prefix = (i == 0) ? (name + " iter " + count + ": ") : "";
            System.out.print(prefix + Integer.toHexString((byte) ((byte) (0xFF) & rcvData[i])) + " ");
        }
        System.out.println();
    }

}

Answer 1

查看代码，因此有两台服务器位于两台不同的机器上我假设正在监听同一个端口999.因此我认为问题可能在于服务器代码。当您回复客户端时，您是否这样做

byte[] rcvData = new byte[5];
DatagramPacket rcvPacket = new DatagramPacket(rcvData, rcvData.length);
socket.receive(rcvPacket);
DatagramPacket sendPacket = new DatagramPacket(rcvPacket.getData(), rcvPacket.getLength(), rcvPacket.getAddress(), rcvPacket.getPort());  // note that here we need to use the received packet information on where to send the response back
socket.send(sendPacket);

很少有其他评论

使构造函数UdpClientRunnable转到其他输入目标端口和目标地址，这样就不需要在if / else里面包含所有if else块了。
从sendAndReceive移除已同步的关键字，因为run已经同步

如何在UDP协议上同步通信？

设置

问题

问题

测试代码

1 个答案: