How to safely call an async method in C# without await

If you want to get the exception "asynchronously", you could do:

  MyAsyncMethod().
    ContinueWith(t => Console.WriteLine(t.Exception),
        TaskContinuationOptions.OnlyOnFaulted);

This will allow you to deal with an exception on a thread other than the "main" thread. This means you don't have to "wait" for the call to MyAsyncMethod() from the thread that calls MyAsyncMethod; but, still allows you to do something with an exception--but only if an exception occurs.

Update:

technically, you could do something similar with await:

try
{
    await MyAsyncMethod().ConfigureAwait(false);
}
catch (Exception ex)
{
    Trace.WriteLine(ex);
}

...which would be useful if you needed to specifically use try/catch (or using) but I find the ContinueWith to be a little more explicit because you have to know what ConfigureAwait(false) means.

You should first consider making GetStringData an async method and have it await the task returned from MyAsyncMethod.

If you're absolutely sure that you don't need to handle exceptions from MyAsyncMethod or know when it completes, then you can do this:

public string GetStringData()
{
  var _ = MyAsyncMethod();
  return "hello world";
}

BTW, this is not a "common problem". It's very rare to want to execute some code and not care whether it completes and not care whether it completes successfully.

Update:

Since you're on ASP.NET and wanting to return early, you may find my blog post on the subject useful. However, ASP.NET was not designed for this, and there's no guarantee that your code will run after the response is returned. ASP.NET will do its best to let it run, but it can't guarantee it.

So, this is a fine solution for something simple like tossing an event into a log where it doesn't really matter if you lose a few here and there. It's not a good solution for any kind of business-critical operations. In those situations, you must adopt a more complex architecture, with a persistent way to save the operations (e.g., Azure Queues, MSMQ) and a separate background process (e.g., Azure Worker Role, Win32 Service) to process them.