多个客户端连接到服务器的 C# 套接字读取缓冲区错误

Question

我编写了一个 Windows C# 应用程序，它可以创建多达 16 个线程。每个线程为远程设备创建一个套接字。每个线程发送命令来读取设备状态。 （每 300 毫秒）当我创建一个或两个线程来读取状态时就可以了。但是当我创建 10 个线程来读取设备状态时，我会在套接字接收缓冲区中得到错误的数据。

我的socket驱动代码请参考以下：

class SocketClient {

    private IPAddress ipAddress;
    private IPEndPoint remoteEP;
    private Socket mSocket;
    private SocketAsyncEventArgs e = new SocketAsyncEventArgs();
    private System.Timers.Timer timer_connection;
    private static byte[] response = new byte[1024];
    private Boolean waittingConnectDone;
    private Boolean boolConnected;
    public SocketClient() {
    }

    private byte[] acknowledge = null;

    public Boolean Connect(String IP, int Port) {
        Boolean bRet = true;
        ipAddress = IPAddress.Parse(IP);
        remoteEP = new IPEndPoint(ipAddress, Port);
        mSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        //mSocket.ReceiveTimeout = GlobalVar.ethernet_timeout;
        mSocket.ReceiveTimeout = 500;

        try {
            waittingConnectDone = false;
            e.RemoteEndPoint = remoteEP;
            e.UserToken = mSocket;
            e.Completed += new EventHandler<SocketAsyncEventArgs>(e_Completed);
            mSocket.ConnectAsync(e);

            if (timer_connection != null) {
                timer_connection.Dispose();
            } else {
                timer_connection = new System.Timers.Timer();
            }
            timer_connection.Interval = 2000;
            timer_connection.Elapsed += new ElapsedEventHandler(timer_connection_Tick);
            timer_connection.Start();
            while (true) {
                if (waittingConnectDone)
                    break;
                Application.DoEvents();
            }
            bRet = boolConnected;

            //sender.Connect(remoteEP);
        } catch {
            Debug.WriteLine("### Ethernet ### Connection Error!");
            bRet = false;
        }
        return bRet;
    }

    private void e_Completed(object sender, SocketAsyncEventArgs e) {
        boolConnected = true;
        waittingConnectDone = true;
    }

    private void timer_connection_Tick(object sender, EventArgs e) {
        if (!mSocket.Connected) {
            timer_connection.Stop();
            boolConnected = false;
            waittingConnectDone = true;
        }
    }

    public void Disconnect() {
        try {
            mSocket.Shutdown(SocketShutdown.Both);
            mSocket.Close();
        } catch {
        }
    }

每个线程使用以下代码读取设备状态：

    private byte[] acknowledge = null;
    private static byte[] response = new byte[1024];

    public byte[] sendCommand(byte[] Cmp_TxData) {
        try {
            bytesSent = mSocket.Send(Cmp_TxData);
            bytesRec = mSocket.Receive(response);

            acknowledge = new byte[bytesRec];
            Array.Copy(response, 0, acknowledge, 0, bytesRec);
        }
        catch
        {
            acknowledge = null;
        }

        return acknowledge;
    }

缓冲区数据错误如下：

TX --> 00-03-01-F4-00-03-44-14

RX

有时我读到正确的数据，但有时数据都是0！

我的套接字驱动程序有什么问题吗？

非常感谢您的帮助！

Answer 1

我没有检查所有发布的代码（我怀疑可能会有更多错误，如果你自己尝试多线程很难），但是这一行：

private static byte[] response = new byte[1024];

绝对是您报告的错误类型的来源。这一行声明了一个在所有线程之间共享的缓冲区。

所以如果多个线程这样做：

bytesRec = mSocket.Receive(response);

此响应缓冲区中的数据可以同时修改。

要解决此特定错误，您可以确保使用[ThreadStatic] 或ThreadLocal 为每个线程创建一个静态缓冲区（例如参见http://reedcopsey.com/2009/11/12/thread-specific-data-becomes-easier-in-net-4-0-via-threadlocalt/）。