有很多地方可以优雅地终止 C# 线程。但是,它们依赖于循环或在循环内执行的 if 条件,这假定该语句将被频繁执行;因此,当设置了 stop
bool 标志时,线程会快速退出。
如果我有一个主题不是这样怎么办?在我的例子中,这是一个设置为从服务器接收数据的线程,该线程经常阻塞从输入流读取数据的调用,因为尚未提供任何数据,因此它会等待。
这是有问题的循环中的线程:
while (true)
{
if (EndThread || Commands.EndRcvThread)
{
Console.WriteLine("Ending thread.");
return;
}
data = "";
received = new byte[4096];
int bytesRead = 0;
try
{
bytesRead = stream.Read(received, 0, 4096);
}
catch (Exception e)
{
Output.Message(ConsoleColor.DarkRed, "Could not get a response from the server.");
if (e.GetType() == Type.GetType("System.IO.IOException"))
{
Output.Message(ConsoleColor.DarkRed, "It is likely that the server has shut down.");
}
}
if (bytesRead == 0)
{
break;
}
int endIndex = received.Length - 1;
while (endIndex >= 0 && received[endIndex] == 0)
{
endIndex--;
}
byte[] finalMessage = new byte[endIndex + 1];
Array.Copy(received, 0, finalMessage, 0, endIndex + 1);
data = Encoding.ASCII.GetString(finalMessage);
try
{
ProcessMessage(data);
}
catch (Exception e)
{
Output.Message(ConsoleColor.DarkRed, "Could not process the server's response (" + data + "): " + e.Message);
}
}
block 顶部的 if
语句执行正常的停止线程设置所做的事情:检查标志,如果已设置则终止线程。但是,通常会发现此线程在 stream.Read
处等待几行。
鉴于此,是否有任何方式可以优雅地终止此线程(即没有 Abort
ing),并清理其资源(有一个客户端需要关闭)?
最佳答案
假设您可以使用异步/任务,完全停止异步和 IO 操作的方法是使用连接到 CancelationTokenSource
的 CancelationToken
。以下代码片段说明了将其应用于简化代码版本时的用法的简化示例。
class MyNetworkThingy
{
public async Task ReceiveAndProcessStuffUntilCancelled(Stream stream, CancellationToken token)
{
var received = new byte[4096];
while (!token.IsCancellationRequested)
{
try
{
var bytesRead = await stream.ReadAsync(received, 0, 4096, token);
if (bytesRead == 0 || !DoMessageProcessing(received, bytesRead))
break; // done.
}
catch (OperationCanceledException)
{
break; // operation was canceled.
}
catch (Exception e)
{
// report error & decide if you want to give up or retry.
}
}
}
private bool DoMessageProcessing(byte[] buffer, int nBytes)
{
try
{
// Your processing code.
// You could also make this async in case it does any I/O.
return true;
}
catch (Exception e)
{
// report error, and decide what to do.
// return false if the task should not
// continue.
return false;
}
}
}
class Program
{
public static void Main(params string[] args)
{
using (var cancelSource = new CancellationTokenSource())
using (var myStream = /* create the stream */)
{
var receive = new MyNetworkThingy().ReceiveAndProcessStuffUntilCancelled(myStream, cancelSource.Token);
Console.WriteLine("Press <ENTER> to stop");
Console.ReadLine();
cancelSource.Cancel();
receive.Wait();
}
}
}
.
关于c# - 我怎样才能优雅地终止一个阻塞的线程?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/29422395/