CancellationTokenSource.Cancel(false)

Question

    static void Main(string[] args)
    {
        CancellationTokenSource cts = new CancellationTokenSource();

        ThreadPool.QueueUserWorkItem(o => DoWork(cts.Token, 100));

        Thread.Sleep(500);

        try
        {
            cts.Token.Register(CancelCallback3);
            cts.Token.Register(CancelCallback2);
            cts.Token.Register(CancelCallback1);



            cts.Cancel(false);
        }
        catch (AggregateException ex)
        {
            foreach (Exception curEx in ex.Data)
            {
                Trace.WriteLine(curEx.ToString());    
            }

        }

        Console.ReadKey();
    }

    private static void CancelCallback1()
    {
        Trace.WriteLine("CancelCallback1 was called");
        throw new Exception("CancellCallback1 exception");
    }


    private static void CancelCallback2()
    {
        Trace.WriteLine("CancelCallback2 was called");
        throw new Exception("CancellCallback2 exception");
    }

    private static void CancelCallback3()
    {
        Trace.WriteLine("CancelCallback3 was called");
    }

    private static void DoWork(CancellationToken cancellationToken, int maxLength)
    {
        int i = 0;
        while (i < maxLength && !cancellationToken.IsCancellationRequested)
        {
            Trace.WriteLine(i++);
            Thread.Sleep(100);
        }
    }

输出为：

0
1
2
3
4
CancelCallback1 was called

根据我希望得到AggregateException的http://msdn.microsoft.com/en-us/library/dd321703.aspx，看起来throwOnFirstException参数在这里没有任何意义。我的代码出了什么问题。

Answer 1

您需要使用Task<>类来获取AggregateException。它是ThreadPool.QueueUserWorkItem()的替代品。

Answer 2

问题是在Visual Studio中缺乏强大的调试经验。我的VS调试器设置被设置为在第一次出现异常时停止。

仅供参考的CancellationTokenSource.Cancel(false)既适用于ThreadPool，也适用于任务。