c# - C# Task.WaitAll() 取消错误处理

Question

我有个问题。我尝试运行多个长时间运行的任务。如果一个失败，我想取消所有其他任务并获得失败异常。下面给出的例子。我想用抛出的异常捕获 AggregateException

 throw new Exception("FailureTask");

但是我捕获的是 OperationCanceledException 而不是 AggregateException，因为我想取消所有其他任务。

    [TestMethod]
    public void TestParallelTaskCancelation()
    {
        var cancellationTokenSource = new CancellationTokenSource();
        Task[] tasks =
        {
            Task.Factory.StartNew(DummyTask, cancellationTokenSource, cancellationTokenSource.Token),
            Task.Factory.StartNew(DummyTask, cancellationTokenSource, cancellationTokenSource.Token),
            Task.Factory.StartNew(DummyTask, cancellationTokenSource, cancellationTokenSource.Token),
            Task.Factory.StartNew(DummyTask, cancellationTokenSource, cancellationTokenSource.Token),
            Task.Factory.StartNew(FailureTask, cancellationTokenSource, cancellationTokenSource.Token)
        };

        try
        {
            Task.WaitAll(tasks, cancellationTokenSource.Token);
        }
        catch (OperationCanceledException e)
        {
            Console.WriteLine(e.GetaAllMessages());
        }
        catch (AggregateException e)
        {
            Console.WriteLine(e.GetaAllMessages());
        }
    }

    private void DummyTask(object o)
    {
        var cancellationToken = (CancellationTokenSource)o;
        while (true)
        {
            Thread.Sleep(10000);
            if (cancellationToken.IsCancellationRequested)
            {
                cancellationToken.Token.ThrowIfCancellationRequested();
            }
        }
    }

    private void FailureTask(object o)
    {
        var cancellationToken = (CancellationTokenSource)o;

        var executionTask = Task.Factory.StartNew(() =>
        {
            Thread.Sleep(1000);
            throw new Exception("FailureTask");
        }, cancellationToken.Token);

        executionTask.ContinueWith(t =>
        {
            cancellationToken.Cancel(false);
            throw new Exception(t.Exception.GetaAllMessages());
        }, TaskContinuationOptions.OnlyOnFaulted);

        if (executionTask.Wait(10 * 1000, cancellationToken.Token)) return;
        //timeout !!!
        throw new Exception("The limit 'Max Seconds Per Query' has been exceeded!!!");
    }`

请帮忙。

Answer 1

这对我有用

public static async void TestParallelTaskCancelation()
    {
        var cancellationTokenSource = new CancellationTokenSource();
        Task[] tasks =
        {
        Task.Factory.StartNew(DummyTask, cancellationTokenSource, cancellationTokenSource.Token),
        Task.Factory.StartNew(DummyTask, cancellationTokenSource, cancellationTokenSource.Token),
        Task.Factory.StartNew(DummyTask, cancellationTokenSource, cancellationTokenSource.Token),
        Task.Factory.StartNew(DummyTask, cancellationTokenSource, cancellationTokenSource.Token),
        Task.Factory.StartNew(FailureTask, cancellationTokenSource, cancellationTokenSource.Token)
        };

        try
        {
           await Task.WhenAll(tasks);
        }
        catch (OperationCanceledException e)
        {
            Console.WriteLine(e.ToString());
        }
        catch (AggregateException e)
        {
            Console.WriteLine(e.ToString());
        }
    }

Answer 2

您应该使用 for throwAggregateException构造函数，而不仅仅是Exception：

throw new AggregateException ("FailureTask");