如果超时后任务仍未完成，Task.Wait(int) 是否会停止任务？

发布于 2024-09-29 14:19:56 字数 300 浏览 3 评论 0 原文

我有一个任务，我预计它需要不到一秒钟的时间才能运行，但如果它需要的时间超过几秒钟，我想取消该任务。

例如：

Task t = new Task(() =>
        {
            while (true)
            {
                Thread.Sleep(500);
            }
        });
t.Start();
t.Wait(3000);

请注意，3000 毫秒后等待到期。超时后任务是被取消还是任务仍在运行？

原文

I have a task and I expect it to take under a second to run but if it takes longer than a few seconds I want to cancel the task.

For example:

Task t = new Task(() =>
        {
            while (true)
            {
                Thread.Sleep(500);
            }
        });
t.Start();
t.Wait(3000);

Notice that after 3000 milliseconds the wait expires. Was the task canceled when the timeout expired or is the task still running?

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╰ゝ天使的微笑 2024-10-06 14:19:56

Task.Wait() 等待指定时间段内的任务完成，并返回任务是否在指定时间（或更早）内完成。任务本身不会被修改，也不依赖于等待。

阅读精彩系列： . NET，.NET 中的并行性 – 第 10 部分，PLINQ 中的取消和 Parallel 类作者：Reed Copsey

以及：并行编程：任务取消

检查以下代码：

var cts = new CancellationTokenSource();

var newTask = Task.Factory.StartNew(state =>
                           {
                              var token = (CancellationToken)state;
                              while (!token.IsCancellationRequested)
                              {
                              }
                              token.ThrowIfCancellationRequested();
                           }, cts.Token, cts.Token);


if (!newTask.Wait(3000, cts.Token)) cts.Cancel();

Task.Wait() waits up to specified period for task completion and returns whether the task completed in the specified amount of time (or earlier) or not. The task itself is not modified and does not rely on waiting.

Read nice series: Parallelism in .NET, Parallelism in .NET – Part 10, Cancellation in PLINQ and the Parallel class by Reed Copsey

And: .NET 4 Cancellation Framework / Parallel Programming: Task Cancellation

Check following code:

var cts = new CancellationTokenSource();

var newTask = Task.Factory.StartNew(state =>
                           {
                              var token = (CancellationToken)state;
                              while (!token.IsCancellationRequested)
                              {
                              }
                              token.ThrowIfCancellationRequested();
                           }, cts.Token, cts.Token);


if (!newTask.Wait(3000, cts.Token)) cts.Cancel();

回复收藏 0 原文

梦旅人picnic 2024-10-06 14:19:56

如果您想取消Task，则应在创建任务时传入CancellationToken。这将允许您从外部取消Task。如果需要，您可以将取消与计时器联系起来。

要使用取消令牌创建任务，请参阅以下示例：

var tokenSource = new CancellationTokenSource();
var token = tokenSource.Token;

var t = Task.Factory.StartNew(() => {
    // do some work
    if (token.IsCancellationRequested) {
        // Clean up as needed here ....
    }
    token.ThrowIfCancellationRequested();
}, token);

要取消 Task，请在 tokenSource 上调用 Cancel()。

If you want to cancel a Task, you should pass in a CancellationToken when you create the task. That will allow you to cancel the Task from the outside. You could tie cancellation to a timer if you want.

To create a Task with a Cancellation token see this example:

var tokenSource = new CancellationTokenSource();
var token = tokenSource.Token;

var t = Task.Factory.StartNew(() => {
    // do some work
    if (token.IsCancellationRequested) {
        // Clean up as needed here ....
    }
    token.ThrowIfCancellationRequested();
}, token);

To cancel the Task call Cancel() on the tokenSource.