Unmangling (pre .NET 4.5) async/await stack traces

Question

Since pre .NET 4.5 runtimes (including SL/WP) are not async-aware, the stack traces they generate show compiler-generated class/method names (like d_15).

Does anyone know of a utility that generate a better stack trace given a runtime stacktrace, an assembly and a pdb?

To be clear: I'm not looking for a complete async stack, just a better view of which method that actually threw the exception

It seems the above statement is not clear enough, so here is an example:

public async void Foo()
{
    await Bar();
}

public async Task Bar()
{
    async SomethingToMakeThisMethodAsync();

    throw new Exception()
}

When the exception is thrown is Bar, the stacktrace will only contain generated method names (d_15()). I don't care that Foo called Bar. I just want to know that Bar was the method that threw the exception

Answer 1

Andrew Stasyuk has a great article in MSDN magazine http://msdn.microsoft.com/en-us/magazine/jj891052.aspx that details Async Causality Chains as a way to aid in debugging in light of the disjoint and confusing stack traces.

Answer 2

Seems like you wasted your rep on bounty since this question was asked few times before, for example, in:

• Stack traces with async/await

which, as I can recall, had few bounties but had not gotten much further than ref to:

• Andrew Stasyuk. Async Causality Chain Tracking

Or in this SO question:

• Debugging Async/Await (Call Stack)

with reference in answer to:

• Stephen Cleary (the blog). Implicit Async Context ("AsyncLocal")

Another similar SO question:

• Is it possible to get a good stack trace with .NET async methods?

I found the collection of references on Parallel Debugging (Parallel Stacks, Parallel Tasks) in Visual Studio 2010 by Daniel Moth to be very helpful

Update:

Having run your code

using System;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
  class Program
  {
    static void Main(string[] args)
    {
        Foo();
    }
    public static async void Foo()
    {
      await Bar();
    }

    public static async Task Bar()
    {
      try
      {
        //async SomethingToMakeThisMethodAsync();
        //to make this async
        await TaskEx.Delay(2000);//await Task.Delay(2000);//in .NET 4.5
        throw new Exception();
      }
      catch (Exception)
      {
        throw new Exception("This is Excptn in Bar() method");
      }
    }
  }
}

in VS2010+Async CTP debug mode (F5), I clearly see my identifying exception message "This is Excptn in Bar() method":

Anyway, it is identified as ConsoleApplication1.Program.<Bar> in stack trace (Locals window) even without any additional marking (catching-rethrowing exception with custom message), i.e. having substituted in above code the Bar() method by:

public static async Task Bar()
{
    //async SomethingToMakeThisMethodAsync();
    //to make this async
     await TaskEx.Delay(2000);//await Task.Delay(2000);//in .NET 4.5
     throw new Exception();
}

I see in stack trace that exception was thrown in ConsoleApplication1.Program.<Bar>:

+ $exception    
{System.Exception: Exception of type 'System.Exception' was thrown.

Server stack trace: 
   at ConsoleApplication1.Program.<Bar>d__3.MoveNext() in R:\###Debugging\#seUnmangling (pre .NET 4.5) asyncawait stack traces\AsyncConsole_Sln\1Cons_Prj\Program.cs:line 29

Exception rethrown at [0]: 
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at ConsoleApplication1.Program.<Foo>d__0.MoveNext() in R:\###Debugging\#seUnmangling (pre .NET 4.5) asyncawait stack traces\AsyncConsole_Sln\1Cons_Prj\Program.cs:line 19

Exception rethrown at [1]: 
   at System.Runtime.CompilerServices.AsyncVoidMethodBuilder.<SetException>b__1(Object state)
   at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
   at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()}   System.Exception