Task.WaitAll，如何找到導致 AggregateException 的任務

Question

假設我得到了以下代碼：

var tasks = BuildTaskList();
try
{
    Task.WaitAll(tasks.ToArray());
}
catch (AggregateException exception)
{

}

我怎么知道哪個任務在 exception.InnerExceptions 中拋出了哪些exception.InnerExceptions ？

Answer 1

您仍然擁有Tasks列表，並且每個Task都有一個Exception屬性。 使用它，您可以確定哪些異常屬於哪個Task 。

但是，如果可以，最好使用Task.WhenAll或TaskFactory.ContinueWhenAll不是阻塞等待。

Answer 2

var throwers = tasks.Where(task => task.Exception != null);

Answer 3

        var t1 = Task.Factory.StartNew(() => Console.WriteLine("Task 1"));
        var t2 = Task.Factory.StartNew(() => Console.WriteLine("Task 2"));
        var t3 = Task.Factory.StartNew(() => { throw new InvalidOperationException(); });
        var t4 = Task.Factory.StartNew(() => Console.WriteLine("Task 4"));

        Task.Factory.ContinueWhenAll(new[] { t1, t2, t3, t4 }, tasks =>
            {
                foreach (var t in tasks)
                {
                    if (t.Status == TaskStatus.Faulted)
                    {
                        // this will run for t3
                        Console.WriteLine("This task has been faulted.");
                    }
                }
            });

Answer 4

選項1（歸功於@theodor-zoulias 評論）：

您可以使用任務名稱設置Exception.Data屬性：

var task1 = Task.Factory.StartNew(() =>
{
    try
    {
        throw new Exception();
    }
    catch (Exception exception)
    {
        exception.Data["task"] = "task1";
        throw exception;
    }
});

var task2 = Task.Factory.StartNew(() =>
{
    try
    {
        throw new Exception();
    }
    catch (Exception exception)
    {
        exception.Data["task"] = "task2";
        throw exception;
    }
});

try
{
    Task.WaitAll(task1, task2);
}
catch (AggregateException ae)
{
    foreach (var exception in ae.InnerExceptions)
    {
        Console.WriteLine($"Exception was thrown by {exception.Data["task"]}");
    }
}

選項2：

如果您不介意丟失異常程序集信息的名稱，您可以根據任務名稱設置拋出異常的Exception.Source ( doc ) 屬性並在迭代時查看它：

var t1 = Task.Factory.StartNew(() => 
{
    throw new Exception() { Source = "t1" };
});
var t2 = Task.Factory.StartNew(() => 
{
    throw new Exception() { Source = "t2" };
});

try
{
    Task.WaitAll(t1, t2);
}
catch (AggregateException ae)
{
    foreach (var exception in ae.InnerExceptions)
    {
        Console.WriteLine($"Exception was thrown by {exception.Source}");
    }
}

將輸出：

異常被 t1 拋出

異常被 t2 拋出