在C#中，處理大量并發連接的推薦方法是使用異步編程模型，例如async/await和Task

1. 首先，創建一個Socket對象來監聽客戶端連接：

using System;
using System.Net;
using System.Net.Sockets;

class Program
{
    static async Task Main(string[] args)
    {
        int port = 8080;
        IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, port);

        using var listener = new Socket(localEndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
        listener.Bind(localEndPoint);
        listener.Listen(100);

        Console.WriteLine($"Server listening on port {port}");

        while (true)
        {
            // Accept incoming connections asynchronously
            var clientSocket = await listener.AcceptAsync();
            HandleClientConnection(clientSocket);
        }
    }

    // ...
}

2. 然后，創建一個HandleClientConnection方法來處理客戶端連接。這里我們使用async/await和Task來實現異步處理：

// ...

static async void HandleClientConnection(Socket clientSocket)
{
    try
    {
        byte[] buffer = new byte[1024];
        int bytesRead;

        while ((bytesRead = await clientSocket.ReceiveAsync(buffer, SocketFlags.None)) > 0)
        {
            // Process the received data
            string receivedData = Encoding.UTF8.GetString(buffer, 0, bytesRead);
            Console.WriteLine($"Received: {receivedData}");

            // Send a response to the client
            byte[] responseData = Encoding.UTF8.GetBytes("Hello from server!");
            await clientSocket.SendAsync(responseData, SocketFlags.None);
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error handling client connection: {ex.Message}");
    }
    finally
    {
        clientSocket.Shutdown(SocketShutdown.Both);
        clientSocket.Close();
    }
}

3. 最后，運行服務器并測試大量并發連接。你可以使用多線程或多進程的客戶端來模擬大量并發連接。

這種方法利用了C#的異步編程特性，可以有效地處理大量并發連接。當然，根據實際需求，你還可以對代碼進行優化，例如使用連接池、限制并發連接數等。