正在使用同步API和线程池开发一个类似于此的TCP服务器：
TcpListener listener;
void Serve(){
while(true){
var client = listener.AcceptTcpClient();
ThreadPool.QueueUserWorkItem(this.HandleConnection, client);
//Or alternatively new Thread(HandleConnection).Start(client)
}
}假设我的目标是以最低的资源使用率处理尽可能多的并发连接：
async Task Serve(){
while(true){
var client = await listener.AcceptTcpClientAsync();
HandleConnectionAsync(client); //fire and forget?
}
}
回答 2
while循环不显式地创建任何线程：
using System;
using System.Collections.Generic;
using System.Net.Sockets;
using System.Text;
using System.Threading.Tasks;
class Program
{
object _lock = new Object(); // sync lock
List<Task> _connections = new List<Task>(); // pending connections
// The core server task
private async Task StartListener()
{
var tcpListener = TcpListener.Create(8000);
tcpListener.Start();
while (true)
{
var tcpClient = await tcpListener.AcceptTcpClientAsync();
Console.WriteLine("[Server] Client has connected");
var task = StartHandleConnectionAsync(tcpClient);
// if already faulted, re-throw any error on the calling context
if (task.IsFaulted)
task.Wait();
}
}
// Register and handle the connection
private async Task StartHandleConnectionAsync(TcpClient tcpClient)
{
// start the new connection task
var connectionTask = HandleConnectionAsync(tcpClient);
// add it to the list of pending task
lock (_lock)
_connections.Add(connectionTask);
// catch all errors of HandleConnectionAsync
try
{
await connectionTask;
// we may be on another thread after "await"
}
catch (Exception ex)
{
// log the error
Console.WriteLine(ex.ToString());
}
finally
{
// remove pending task
lock (_lock)
_connections.Remove(connectionTask);
}
}
// Handle new connection
private async Task HandleConnectionAsync(TcpClient tcpClient)
{
await Task.Yield();
// continue asynchronously on another threads
using (var networkStream = tcpClient.GetStream())
{
var buffer = new byte[4096];
Console.WriteLine("[Server] Reading from client");
var byteCount = await networkStream.ReadAsync(buffer, 0, buffer.Length);
var request = Encoding.UTF8.GetString(buffer, 0, byteCount);
Console.WriteLine("[Server] Client wrote {0}", request);
var serverResponseBytes = Encoding.UTF8.GetBytes("Hello from server");
await networkStream.WriteAsync(serverResponseBytes, 0, serverResponseBytes.Length);
Console.WriteLine("[Server] Response has been written");
}
}
// The entry point of the console app
static void Main(string[] args)
{
Console.WriteLine("Hit Ctrl-C to exit.");
new Program().StartListener().Wait();
}
}或者，代码可能如下所示：
// Handle new connection
private static Task HandleConnectionAsync(TcpClient tcpClient)
{
return Task.Run(async () =>
{
using (var networkStream = tcpClient.GetStream())
{
var buffer = new byte[4096];
Console.WriteLine("[Server] Reading from client");
var byteCount = await networkStream.ReadAsync(buffer, 0, buffer.Length);
var request = Encoding.UTF8.GetString(buffer, 0, byteCount);
Console.WriteLine("[Server] Client wrote {0}", request);
var serverResponseBytes = Encoding.UTF8.GetBytes("Hello from server");
await networkStream.WriteAsync(serverResponseBytes, 0, serverResponseBytes.Length);
Console.WriteLine("[Server] Response has been written");
}
});
}如果这将是一个库代码，那么执行环境确实是未知的
private static Task StartListener()
{
return Task.Run(async () =>
{
var tcpListener = TcpListener.Create(8000);
tcpListener.Start();
while (true)
{
var tcpClient = await tcpListener.AcceptTcpClientAsync();
Console.WriteLine("[Server] Client has connected");
var task = StartHandleConnectionAsync(tcpClient);
// if already faulted, re-throw any error on the calling context
if (task.IsFaulted)
task.Wait();
}
});
}建议使用Task.Run(() => HandleConnection(client));
取代await Serve();(例如)：
var serverTasks =
Enumerable.Range(0, Environment.ProcessorCount)
.Select(_ => Serve());
await Task.WhenAll(serverTasks);和开发者交流更多问题细节吧，去 写回答
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