像这样的东西怎么样?

    const int x = 3000;
    const int y = 1000;

    static void Main(string[] args)
    {
        // Your scheduler
        TaskScheduler scheduler = TaskScheduler.Default;

        Task nonblockingTask = new Task(() =>
            {
                CancellationTokenSource source = new CancellationTokenSource();

                Task t1 = new Task(() =>
                    {
                        while (true)
                        {
                            // Do something
                            if (source.IsCancellationRequested)
                                break;
                        }
                    }, source.Token);

                t1.Start(scheduler);

                // Wait for task 1
                bool firstTimeout = t1.Wait(x);

                if (!firstTimeout)
                {
                    // If it hasn't finished at first timeout display message
                    Console.WriteLine("Message to user: the operation hasn't completed yet.");

                    bool secondTimeout = t1.Wait(y);

                    if (!secondTimeout)
                    {
                        source.Cancel();
                        Console.WriteLine("Operation stopped!");
                    }
                }
            });

        nonblockingTask.Start();
        Console.WriteLine("Do whatever you want...");
        Console.ReadLine();
    }

您可以使用任务。等待选项，不阻塞主线程使用另一个任务。

这个怎么样:

int timeout = 1000;
var task = SomeOperationAsync();
if (await Task.WhenAny(task, Task.Delay(timeout)) == task) {
    // task completed within timeout
} else { 
    // timeout logic
}

这里有一篇很棒的博客文章“制定任务”。TimeoutAfter Method”(来自MS并行库团队)提供了关于这类事情的更多信息。

补充:在我的回答的评论请求，这里是一个扩展的解决方案，包括取消处理。请注意，将取消传递给任务和计时器意味着在代码中可以经历多种取消方式，您应该确保测试并确信您正确地处理了所有这些方法。不要让各种组合的机会，并希望您的计算机在运行时做正确的事情。

int timeout = 1000;
var task = SomeOperationAsync(cancellationToken);
if (await Task.WhenAny(task, Task.Delay(timeout, cancellationToken)) == task)
{
    // Task completed within timeout.
    // Consider that the task may have faulted or been canceled.
    // We re-await the task so that any exceptions/cancellation is rethrown.
    await task;

}
else
{
    // timeout/cancellation logic
}

为了它的乐趣，我做了一个“OnTimeout”扩展任务。超时时Task执行所需的内联lambda Action()并返回true，否则返回false。

public static async Task<bool> OnTimeout<T>(this T t, Action<T> action, int waitms) where T : Task
{
    if (!(await Task.WhenAny(t, Task.Delay(waitms)) == t))
    {
        action(t);
        return true;
    } else {
        return false;
    }
}

OnTimeout扩展返回一个bool结果，可以分配给一个变量，就像这个例子调用UDP套接字Async:

var t = UdpSocket.ReceiveAsync();

var timeout = await t.OnTimeout(task => {
    Console.WriteLine("No Response");
}, 5000);

在timeout lambda中可以访问“task”变量以进行更多处理。

Action接收对象的使用可能会启发其他各种扩展设计。

我将这里的一些其他答案和另一个线程上的这个答案重新组合成一个try风格的扩展方法。如果您想要一个扩展方法，这有一个好处，同时避免超时时出现异常。

public static async Task<bool> TryWithTimeoutAfter<TResult>(this Task<TResult> task,
    TimeSpan timeout, Action<TResult> successor)
{

    using var timeoutCancellationTokenSource = new CancellationTokenSource();
    var completedTask = await Task.WhenAny(task, Task.Delay(timeout, timeoutCancellationTokenSource.Token))
                                  .ConfigureAwait(continueOnCapturedContext: false);

    if (completedTask == task)
    {
        timeoutCancellationTokenSource.Cancel();

        // propagate exception rather than AggregateException, if calling task.Result.
        var result = await task.ConfigureAwait(continueOnCapturedContext: false);
        successor(result);
        return true;
    }
    else return false;        
}     

async Task Example(Task<string> task)
{
    string result = null;
    if (await task.TryWithTimeoutAfter(TimeSpan.FromSeconds(1), r => result = r))
    {
        Console.WriteLine(result);
    }
}    

像这样的东西怎么样?

    const int x = 3000;
    const int y = 1000;

    static void Main(string[] args)
    {
        // Your scheduler
        TaskScheduler scheduler = TaskScheduler.Default;

        Task nonblockingTask = new Task(() =>
            {
                CancellationTokenSource source = new CancellationTokenSource();

                Task t1 = new Task(() =>
                    {
                        while (true)
                        {
                            // Do something
                            if (source.IsCancellationRequested)
                                break;
                        }
                    }, source.Token);

                t1.Start(scheduler);

                // Wait for task 1
                bool firstTimeout = t1.Wait(x);

                if (!firstTimeout)
                {
                    // If it hasn't finished at first timeout display message
                    Console.WriteLine("Message to user: the operation hasn't completed yet.");

                    bool secondTimeout = t1.Wait(y);

                    if (!secondTimeout)
                    {
                        source.Cancel();
                        Console.WriteLine("Operation stopped!");
                    }
                }
            });

        nonblockingTask.Start();
        Console.WriteLine("Do whatever you want...");
        Console.ReadLine();
    }

您可以使用任务。等待选项，不阻塞主线程使用另一个任务。

安德鲁·阿诺特(Andrew Arnott)回答的几个变体:

If you want to wait for an existing task and find out whether it completed or timed out, but don't want to cancel it if the timeout occurs: public static async Task<bool> TimedOutAsync(this Task task, int timeoutMilliseconds) { if (timeoutMilliseconds < 0 || (timeoutMilliseconds > 0 && timeoutMilliseconds < 100)) { throw new ArgumentOutOfRangeException(); } if (timeoutMilliseconds == 0) { return !task.IsCompleted; // timed out if not completed } var cts = new CancellationTokenSource(); if (await Task.WhenAny( task, Task.Delay(timeoutMilliseconds, cts.Token)) == task) { cts.Cancel(); // task completed, get rid of timer await task; // test for exceptions or task cancellation return false; // did not timeout } else { return true; // did timeout } } If you want to start a work task and cancel the work if the timeout occurs: public static async Task<T> CancelAfterAsync<T>( this Func<CancellationToken,Task<T>> actionAsync, int timeoutMilliseconds) { if (timeoutMilliseconds < 0 || (timeoutMilliseconds > 0 && timeoutMilliseconds < 100)) { throw new ArgumentOutOfRangeException(); } var taskCts = new CancellationTokenSource(); var timerCts = new CancellationTokenSource(); Task<T> task = actionAsync(taskCts.Token); if (await Task.WhenAny(task, Task.Delay(timeoutMilliseconds, timerCts.Token)) == task) { timerCts.Cancel(); // task completed, get rid of timer } else { taskCts.Cancel(); // timer completed, get rid of task } return await task; // test for exceptions or task cancellation } If you have a task already created that you want to cancel if a timeout occurs: public static async Task<T> CancelAfterAsync<T>(this Task<T> task, int timeoutMilliseconds, CancellationTokenSource taskCts) { if (timeoutMilliseconds < 0 || (timeoutMilliseconds > 0 && timeoutMilliseconds < 100)) { throw new ArgumentOutOfRangeException(); } var timerCts = new CancellationTokenSource(); if (await Task.WhenAny(task, Task.Delay(timeoutMilliseconds, timerCts.Token)) == task) { timerCts.Cancel(); // task completed, get rid of timer } else { taskCts.Cancel(); // timer completed, get rid of task } return await task; // test for exceptions or task cancellation }

另一个注释是，如果超时没有发生，这些版本将取消计时器，因此多次调用不会导致计时器堆积。

sjb