Exceptional Async Handling: Listing 1.

Async code to purposely throw exceptions.

static void Main(string[] args)
{
  GeneralThreadAffineContext.Run(() => Sample());
}

private async static void Sample()
{
  var result = await FindTotalPeopleAtSchool();
  Console.WriteLine("Number of people at school: {0}", result);

  if (Debugger.IsAttached)
  {
    Console.WriteLine("Press any key to exit.");
    Console.ReadKey();
  }
}

private async static Task<int> FindTotalPeopleAtSchool()
{
  try
  {
    var getKidsTask = Task.Factory.StartNew(() =>
                                              {
                                                Thread.Sleep(1000);
                                                 throw new CountingException("kids");
                                                return 88;
                                              });
    var getStaffTask = Task.Factory.StartNew(() =>
                                               {
                                                 Thread.Sleep(1000);
                                                 throw new CountingException("staff");
                                                 return 200;
                                               });

    var kids = await getKidsTask;
    var staff = await getStaffTask;

    return kids + staff;
  }
  catch (CountingException ex)
  {
    Console.WriteLine("Something went wrong counting {0}", ex.Message);
  }

  return 0;
}

About the Author

Patrick Steele is a senior .NET developer with Billhighway in Troy, Mich. A recognized expert on the Microsoft .NET Framework, he’s a former Microsoft MVP award winner and a presenter at conferences and user group meetings.