Question

我有一个TCP服务器（实现为Windows服务），用于在车辆跟踪应用程序中监听GPS设备，在从其操作的随机时间段后我得到以下错误：“每个套接字地址只有一次使用（协议）通常允许/网络地址/端口。“虽然我确信我在使用它后关闭每个插槽。所以有人能告诉我这里有什么问题我在Windows Server 2008注册表中使用（65534）的MaxUserPort值和TCPTimeWaitDelay值（30秒）吗？

这是代码： 1）主线程：

 private void MainThread() {
        byte[] bytes = new Byte[1024];

        IPEndPoint localEndPoint = new IPEndPoint(0, this.port);

        Socket listener = new Socket(AddressFamily.InterNetwork,
            SocketType.Stream, ProtocolType.Tcp );
        // Addedd on [20/03/2012] by Sherif Mosaad for handling socket exceptions ...
        //listener.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, (int)1);

        try {
            listener.Bind(localEndPoint);
            listener.Listen(100);

            while (active) {
                mainDone.Reset();

                listener.BeginAccept(new AsyncCallback(AcceptCallback),listener);

                while (active)
                    if (mainDone.WaitOne(100, true))
                        break;
            }
            listener.Shutdown(SocketShutdown.Both);
            listener.Close();
            Thread.Sleep(2000);

        } catch (Exception e) {
            if (OnError != null)
                OnError(this, e.ToString());
            LogManager.LogError(e, "TCPSimpleServer MainThread"); 
        }
    }

2）AcceptCallback处理程序：

private void AcceptCallback(IAsyncResult ar) {
        mainDone.Set();

        Socket listener = (Socket)ar.AsyncState;
        Socket handler = null;
        try
        {
            handler = listener.EndAccept(ar);
        }
        catch 
        {
            try
            {
                listener.Shutdown(SocketShutdown.Both);
                listener.Close();
                Thread.Sleep(2000);
            }
            catch { return; }
        }

        if (OnConnect != null)
            OnConnect(this, handler);

        StateObject state = new StateObject();

        state.workSocket = handler;
        state.endPoint = (IPEndPoint)handler.RemoteEndPoint;
        stateObjectDictionary.Add(state, state.workSocket);
        handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
            new AsyncCallback(ReadCallback), state);
    }

3）ReadCallback处理程序：

 private void ReadCallback(IAsyncResult ar) {
        String content = String.Empty;
        StateObject state = (StateObject)ar.AsyncState;
        Socket handler = state.workSocket;

        int bytesRead = 0;
        try
        {
            bytesRead = handler.EndReceive(ar);
        }
        catch (Exception e)
        {
            // Connection closed by client
            if (OnDisconnect != null)
                OnDisconnect(this, state.endPoint);
            return;
        }

        if (bytesRead > 0)
        {
            string data = Encoding.ASCII.GetString(state.buffer, 0, bytesRead);
            if (OnDataAvailable != null)
                OnDataAvailable(this, handler, data);
            try
            {
                handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                    new AsyncCallback(ReadCallback), state);
            }
            catch (Exception e)
            {
                // Connection closed by client
                if (OnDisconnect != null)
                    OnDisconnect(this, state.endPoint);
                return;
            }
        }
        else
        {
            // Connection closed by peer
            if (OnDisconnect != null)
                OnDisconnect(this, state.endPoint);
        }
    }

最后是状态对象：

public class StateObject
    {
        public Socket workSocket = null;
        public const int BufferSize = 1024;
        public byte[] buffer = new byte[BufferSize];
        public StringBuilder sb = new StringBuilder();
        public IPEndPoint endPoint;
    }

请帮忙吗？

Answer 1

有竞争条件。您调用mainDone.Set，允许另一个线程继续BeginAccept，同时当前线程移向EndAccept。哪个会先到达那里？如果您在完成上一次接受之前开始接受，我怀疑可能会弹出此错误。

修正？您需要在致电mainDone

之后设置EndAccept事件
更好的是，遵循一个没有同步原语的简单模式。我概述了一个here。

TCP服务器：“通常只允许使用每个套接字地址（协议/网络地址/端口）。”

1 个答案: