C# TCP 套接字性能随着应用程序运行而下降

Question

我编写了一个 C# 服务器应用程序。服务器使用异步 TCP 套接字。

数据包是 80-180 字节的数据。

为了性能测试，我有一个客户端连接并连续发送数据包。调试前 100 个数据包 (0-100) 在大约 5 秒内接收。当服务器接收到数据包 #300-400 时，接收数据包大约需要 30 秒。随着更多的接收发生，性能继续下降。

我环顾四周，未能找到解决方案。我已经尝试设置 Socket.NoDelay 标志以防 Nagle 算法抑制服务器。

我已禁用服务器内的所有功能；所以它只是接收以确保我不会在其他代码中失去性能。

我还检查了我的 CPU 使用率，大约是 13%。我有超过 2 GB 的可用内存。运行应用程序时，内存不会不断增长，利用率也很低。

我对接下来要调试和研究的内容一头雾水......

编辑:添加代码示例

public void StartListening()
    {

        try
        {
            IPAddress ipAddress = IPAddress.Parse("192.168.2.60");
            IPEndPoint localEndPoint = new IPEndPoint(ipAddress, m_Port);
            m_MainSocket = new Socket(localEndPoint.Address.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
            m_MainSocket.NoDelay = true;
            m_MainSocket.Bind(localEndPoint);
            m_MainSocket.Listen(10);
            m_MainSocket.BeginAccept(new AsyncCallback(clientConnected), null);

            System.Diagnostics.Debug.WriteLine("Listening on:Local IP Address: " + localEndPoint.Address.ToString() + " Port :" + localEndPoint.Port.ToString() + "\n");
        }
        catch (SocketException se)
        {
            System.Diagnostics.Debug.WriteLine("Listening Exception \n");
            System.Diagnostics.Debug.WriteLine(se.Message);
        }
    }

    void clientConnected(IAsyncResult ar)
    {
        try
        {
            SocketState state = new SocketState(m_MainSocket.EndAccept(ar));
            Client client = new Client(state);

            if (client.SocketState.clientSocket.Connected)
            {
                System.Diagnostics.Debug.WriteLine("Client #?????? Connected \n");
                AddLogText("Client #?????? Connected \r\n\r\n");
                waitForData(client);
                SetSendButton(true);
            }

            m_MainSocket.BeginAccept(new AsyncCallback(clientConnected), null);
        }
        catch (ObjectDisposedException)
        {
           System.Diagnostics.Debug.WriteLine("Client Connected: Socket has been closed\n");
        }
        catch (SocketException se)
        {
            System.Diagnostics.Debug.WriteLine("Client Connected Exception \n");
            System.Diagnostics.Debug.WriteLine(se.Message);
        }
    }

    void waitForData(Client client)
    {
        try
        {
            SocketState state = new SocketState(client.SocketState.clientSocket);
            client.SocketState.clientSocket = null; 
            client.SocketState = state;
            client.SocketState.clientSocket.BeginReceive(client.SocketState.DataBuffer, 0, client.SocketState.DataBuffer.Length, SocketFlags.None, new AsyncCallback(readDataCallback), client);
        }
        catch (SocketException se)
        {
            System.Diagnostics.Debug.WriteLine("Wait For Data Exception \n");
            System.Diagnostics.Debug.WriteLine(se.Message);
        }

    }

    public void readDataCallback(IAsyncResult ar)
    {
        Client client = (Client)ar.AsyncState;
        try
        {                
            // Read data from the client socket.
            int iRx = client.SocketState.clientSocket.EndReceive(ar);
            client.SocketState.SB.Append(Encoding.ASCII.GetString(client.SocketState.DataBuffer, 0, iRx));
            string sPacketString = client.SocketState.SB.ToString();

            Server formServer = this;
            Packet_Helper packet_helper = new Packet_Helper(sPacketString, formServer);

            Packet packet = new Packet(sPacketString);
            client.SerialNumber = packet.SerialNumber;
            client.FirmwareVersion = packet.FirmwareVersion;
            client.ProductID = packet.ProductID;
            client.HardwareVersion = packet.HardwareVersion;
            if (!m_Clients.ContainsKey(packet.SerialNumber))
            {
                m_Clients.Add(packet.SerialNumber, client);
                UpdateClientList();
                string[] packets = client.refreshAll();
                for (int i = 0; i < packets.Length; i++)
                {
                    byte[] byteData = Encoding.ASCII.GetBytes(packets[i]);
                    client.SocketState.clientSocket.BeginSend(byteData, 0, byteData.Length, SocketFlags.None, new AsyncCallback(SendCallback), client);
                    AddPacketsSentText(packets[i] + "--" + (iSent++).ToString() + "\r\n\r\n");
                }
            }

            System.Diagnostics.Debug.WriteLine("Read " + sPacketString.Length.ToString() + " bytes from " + client.SerialNumber + "\n" + sPacketString + "\n");
            AddLogText("Read " + sPacketString.Length.ToString() + " bytes from " + client.SerialNumber + " \r\n");
            AddLogText(sPacketString.ToString() + "\r\n\r\n");

            waitForData(client);
        }
        catch (ObjectDisposedException)
        {
            System.Diagnostics.Debugger.Log(0, "1", "\nOnDataReceived: Socket has been closed\n");
        }
        catch (SocketException se)
        {
            if (se.ErrorCode == 10054) // Error code for Connection reset by peer
            {
                string sclientSerial = "??????";
                if (client.SerialNumber != null || client.SerialNumber != "")
                    sclientSerial = client.SerialNumber;
                AddLogText("Client " + sclientSerial + " Disconnected" + "\r\n\r\n");
                System.Diagnostics.Debug.WriteLine("Client " + sclientSerial + " Disconnected" + "\n");

                m_Clients.Remove(sclientSerial);
                UpdateClientList();
            }
            else
            {
                System.Diagnostics.Debug.WriteLine("Read Data Exception \n");
                System.Diagnostics.Debug.WriteLine(se.Message);
            }
        }
    }


class SocketState
{
    private Socket m_ClientSocket;                   //Socket connection to the client
    private byte[] m_DataBuffer = new byte[256];        //Buffer to store the data sent by the client
    private StringBuilder m_SB = new StringBuilder();  //for building recieved data into a string 

    /// <summary>
    /// Gets or Sets the client Socket
    /// </summary>
    public Socket clientSocket
    {
        get { return m_ClientSocket; }
        set { m_ClientSocket = value; }
    }

    /// <summary>
    /// Gets the DataBuffer
    /// </summary>
    public byte[] DataBuffer
    {
        get { return m_DataBuffer; }
        set { DataBuffer = value; }
    }

    /// <summary>
    /// Gets or Sets the SB
    /// </summary>
    public StringBuilder SB
    {
        get { return m_SB; }
        set { m_SB = value; }
    }

    public SocketState(Socket socket)
    {
        m_ClientSocket = socket;
        m_ClientSocket.ReceiveBufferSize = 256;
        m_ClientSocket.NoDelay = true;
        //m_DataBuffer = Enumerable.Repeat((byte)0, 256).ToArray();
    }
}      

编辑:添加了 AddLogText() 函数。此函数用于将文本添加到 UI 中的文本框。

//Delegate - 启用异步调用以设置 tb_ListeningLog 的文本属性

delegate void AddLogTextCallback(string text);

private void AddLogText(string text)
    {
        // InvokeRequired required compares the thread ID of the
        // calling thread to the thread ID of the creating thread.
        // If these threads are different, it returns true.
        if (this.tb_ListeningLog.InvokeRequired)
        {
            AddLogTextCallback d = new AddLogTextCallback(AddLogText);
            this.Invoke(d, new object[] { text });
        }
        else
        {
            this.tb_ListeningLog.Text += text;
            tb_ListeningLog.SelectionStart = tb_ListeningLog.Text.Length;
            tb_ListeningLog.ScrollToCaret();
        }
    }

Answer 1

我对这个答案有点摸不着头脑，但您发布的代码肯定有帮助。

随着时间的推移，您可能会看到性能下降的原因是 readDataCallback 方法中的代码。按照您设置的方式，数据处理是在您进行另一次接收之前完成的。这意味着随着处理时间的增加，接收数据之间的持续时间也会增加。

我不知道您的许多方法中的代码是什么，但您通常应该查看可能需要一段时间才能完成的任何循环。如果您无法通过查看代码找到瓶颈，请尝试找出完成时间最长的方法并继续缩小代码范围。

例如(我猜瓶颈在这部分代码中):

if (!m_Clients.ContainsKey(packet.SerialNumber))
{
    m_Clients.Add(packet.SerialNumber, client);

    AddLogText("Running UpdateClientList\r\n");

    UpdateClientList();

    AddLogText("Doing client.refreshAll\r\n");

    string[] packets = client.refreshAll();

    AddLogText("Doing for loop\r\n");

    for (int i = 0; i < packets.Length; i++)
    {
        byte[] byteData = Encoding.ASCII.GetBytes(packets[i]);
        client.SocketState.clientSocket.BeginSend(byteData, 0, byteData.Length, SocketFlags.None, new AsyncCallback(SendCallback), client);
        AddPacketsSentText(packets[i] + "--" + (iSent++).ToString() + "\r\n\r\n");
    }
}

只需用眼睛观察每种方法之间的时间量，或者使用 Stopwatch 或 DateTime 来显示准确的时间。

此外，如果您发现代码的行为无法提高效率，您可以尝试在单独的线程中处理数据。不过，由于手头的问题，我假设这种行为是不需要的。

---

对于您的 AddLogText 方法，请尝试使用 tb_ListeningLog.Text.AppendText 而不是 +=。