c# - .NET TCP 服务器稳定性问题

Question

我已经使用 TcpListener 和 SocketClient 构建了一个基本的 .NET 服务器-客户端基础结构。它是多线程和异步的。问题是，当同时连接超过 30 个客户端时，服务器有时会崩溃。

尽管我确实使用了相当多的 Try-Catch block 来确保记录所有异常，但我仍无法找到崩溃的原因。

所以我在想，我可能在服务器代码中做错了概念上的事情。我希望你们能帮助我找到这些崩溃的原因。代码如下:

启动服务器并监听连接:

 public void StartServer()
    {
        isConnected = true;
        listener.Start();
        connectionThread = new Thread(new ThreadStart(ListenForConnection));
        connectionThread.Start();
    }

    private void ListenForConnection()
    {
        while (isConnected)
        {
            try
            {
                TcpClient client = listener.AcceptTcpClient();
                ClientConnection connection = new ClientConnection(this, client);
                connections.Add(connection);
            }
            catch (Exception ex)
            {
                log.Log("Exception in ListenForConnection: " + ex.Message, LogType.Exception);
            }
        }
    }

ClientConnection 类:

 public class ClientConnection : IClientConnection
{
    private TcpClient client;
    private ISocketServer server;
    private byte[] data;
    private object metaData;

    public TcpClient TcpClient
    {
        get { return client; }
    }

    internal ClientConnection(ISocketServer server, TcpClient client)
    {
        this.client = client;
        this.server = server;

        data = new byte[client.ReceiveBufferSize];

        lock (client.GetStream())
        {
            client.GetStream().BeginRead(data, 0, client.ReceiveBufferSize, ReceiveMessage, null);
        }
    }

    internal void ReceiveMessage(IAsyncResult ar)
    {
        int bytesRead;

        try
        {
            lock (client.GetStream())
            {
                bytesRead = client.GetStream().EndRead(ar);
            }

            if (bytesRead < 1)
                return;

            byte[] toSend = new byte[bytesRead];
            for (int i = 0; i < bytesRead; i++)
                toSend[i] = data[i];

            // Throws an Event with the data in the GUI Dispatcher Thread
            server.ReceiveDataFromClient(this, toSend);

            lock (client.GetStream())
            {
                client.GetStream().BeginRead(data, 0, client.ReceiveBufferSize, ReceiveMessage, null);
            }
        }
        catch (Exception ex)
        {
            Disconnect();
        }
    }

    public void Disconnect()
    {
        // Disconnect Client
    }


}

并将数据从服务器发送到一个或所有客户端:

public void SendDataToAll(byte[] data)
    {
        BinaryWriter writer;

        try
        {
            foreach (IClientConnection connection in connections)
            {
                writer = new BinaryWriter(connection.TcpClient.GetStream());
                writer.Write(data);
                writer.Flush();
            }
        }
        catch (Exception ex)
        {
            // Log
        }
    }

    public void SendDataToOne(IClientConnection client, byte[] data)
    {
        BinaryWriter writer;

        try
        {
            writer = new BinaryWriter(client.TcpClient.GetStream());
            writer.Write(data);
            writer.Flush();
        }
        catch (Exception ex)
        {
            // Log
        }
    }

有时服务器崩溃了，我真的不知道从哪里开始寻找问题。如果需要，我可以提供更多代码。

非常感谢任何帮助:-)安德烈

Answer 1

您应该使对连接字段的访问成为线程安全的。

在 SendData 中，您将遍历连接并将数据发送到每个客户端。如果在执行 foreach 循环时有新的客户端连接，您将收到异常消息“集合已修改；枚举操作可能无法执行”，因为在迭代集合时集合已被修改，这是不允许的。

将SendDataToAll中的行修改为

foreach (IClientConnection connection in connections.ToList())

使问题消失(解决方案由 Collection was modified; enumeration operation may not execute 提供)。