c# - AggregateException.Flatten() 丢失堆栈跟踪信息。丢失的信息重要还是不重要？

Question

文档 on MSDN对于 AggregateException.Flatten 方法，说明如下:“如果任何内部异常本身就是 AggregateException 的实例，则此方法将递归地展平所有这些异常。新 AggregateException 中返回的内部异常将是所有内部异常的并集以提供的 AggregateException 实例为根的异常树。”

这听起来很可疑，好像我们会丢失堆栈跟踪信息，所以我看了一下实现 on Reference Source ，而且看起来堆栈跟踪信息确实会丢失。

所以我们进行了测试:

try
{
    try
    {
        try
        {
            throw new InvalidOperationException();
        }
        catch (Exception e)
        {
            try
            {
                throw new FormatException();
            }
            catch (Exception e2)
            {
                throw new AggregateException(e, e2);
            }
        }
    }
    catch (Exception e)
    {
        try
        {
            throw new NotImplementedException();
        }
        catch (Exception e2)
        {
            throw new AggregateException(e, e2);
        }
    }
}
catch (Exception e)
{
    File.AppendAllText(@"C:\tmp.txt", e.ToString());
    File.AppendAllText(@"C:\tmp.txt", ((AggregateException)e).Flatten().ToString());
}

测试输出如下:

System.AggregateException: One or more errors occurred. ---> System.AggregateException: One or more errors occurred. ---> System.InvalidOperationException: Operation is not valid due to the current state of the object.
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 29
   --- End of inner exception stack trace ---
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 39
   --- End of inner exception stack trace ---
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 51
---> (Inner Exception #0) System.AggregateException: One or more errors occurred. ---> System.InvalidOperationException: Operation is not valid due to the current state of the object.
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 29
   --- End of inner exception stack trace ---
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 39
---> (Inner Exception #0) System.InvalidOperationException: Operation is not valid due to the current state of the object.
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 29<---

---> (Inner Exception #1) System.FormatException: One of the identified items was in an invalid format.
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 35<---
<---

---> (Inner Exception #1) System.NotImplementedException: The method or operation is not implemented.
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 47<---
System.AggregateException: One or more errors occurred. ---> System.NotImplementedException: The method or operation is not implemented.
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 47
   --- End of inner exception stack trace ---
---> (Inner Exception #0) System.NotImplementedException: The method or operation is not implemented.
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 47<---

---> (Inner Exception #1) System.InvalidOperationException: Operation is not valid due to the current state of the object.
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 29<---

---> (Inner Exception #2) System.FormatException: One of the identified items was in an invalid format.
   at ConsoleApplication6.Program.Main(String[] args) in C:\Projects\ConsoleApplication6\ConsoleApplication6\Program.cs:line 35<---

请注意，扁平化的 AggregateException 中未提及第 39 行!!!

丢失的信息重要吗？还是有什么原因使我们在展平 AggregateException 时丢失第 39 行无关紧要？

Answer 1

如果我正确理解您的示例，您是说在抛出 AggregateException 时创建的堆栈跟踪丢失了。这是预期的，因为 Flatten() 将过滤掉属于 InnerExceptions 层次结构的任何 AggregateExceptions。我不会说信息丢失了，因为在大多数情况下有用的信息将在非 AggregateException 实例中。