相关疑难解决方法(0)

我尝试在取消下面的任务时运行一个简单的例子

CancellationTokenSource tokenSource2 = new CancellationTokenSource();

CancellationToken token2 = tokenSource2.Token;


Task task2 = new Task(() =>
{
    for (int i = 0; i < int.MaxValue; i++)
    {
        token2.ThrowIfCancellationRequested();
        Thread.Sleep(100);
        Console.WriteLine("Task 2 - Int value {0}", i);
    }
}, token2);

task2.Start();

Console.WriteLine("Press any key to cancel the task");
Console.ReadLine();

tokenSource2.Cancel();
Console.WriteLine("Task 2 cancelled? {0}", task2.IsCanceled);

我预计 Console.WriteLine("Task 2 cancelled? {0}", task2.IsCanceled);会打印**"Task 2 cancelled? True"**,但它打印"假".

你知道发生了什么吗？这是预期的行为吗？谢谢.

编辑:确保在调用取消请求之前未完成任务.我加了Console.ReadLine().

当我取消任务时,等待结果仍然为IsCanceled属性返回true.似乎有些事情出了问题.

请指教.这是代码:

CancellationTokenSource _cancelLationToken = new CancellationTokenSource();

private async void Button_Click(object sender, EventArgs e)
{
    _cancelLationToken = new CancellationTokenSource();
    _cancelLationToken.Token.Register(theCallBack);
    var myTaskToWaitFor = Task.Factory.StartNew(() => WorkHard(_cancelLationToken.Token), _cancelLationToken.Token);
    await myTaskToWaitFor;

    int i=0;

    if(myTaskToWaitFor.IsCanceled)
        i = i; //breakpoint for debugging
    else
        i = i; //breakpoint for debugging <== always ends here... :-(
}

private void WorkHard(CancellationToken token)
{
    for(int i = 0; i < 100000000; i++)
        if(token.IsCancellationRequested)
            break;
        else
            Math.Acos(Math.Pow(i, i / 10000000));
}

public void theCallBack()
{
    //todo: do something
} …

我有以下示例代码:

static class Program
{
    static void Main()
    {
        var cts = new CancellationTokenSource();

        var task = Task.Factory.StartNew(
            () =>
                {
                    try
                    {
                        Console.WriteLine("Task: Running");
                        Thread.Sleep(5000);
                        Console.WriteLine("Task: ThrowIfCancellationRequested");
                        cts.Token.ThrowIfCancellationRequested();
                        Thread.Sleep(2000);
                        Console.WriteLine("Task: Completed");
                    }
                    catch (Exception exception)
                    {
                        Console.WriteLine("Task: " + exception.GetType().Name);
                        throw;
                    }
                }).ContinueWith(t => Console.WriteLine("ContinueWith: cts.IsCancellationRequested = {0}, task.IsCanceled = {1}, task.Exception = {2}", cts.IsCancellationRequested, t.IsCanceled, t.Exception == null ? "null" : t.Exception.GetType().Name));

        Thread.Sleep(1000);

        Console.WriteLine("Main: Cancel");
        cts.Cancel();

        try
        {
            Console.WriteLine("Main: Wait");
            task.Wait();
        }
        catch (Exception exception)
        {
            Console.WriteLine("Main: Catch …