CODEWITHSUNDEEP
c#asynchronousasync-await
Boris
Boris

Reputation: 1467

Continuation not running C#

Consider the following code

class Program
{

    static void Continue()
    {
        Console.Out.WriteLine("Continue t1"); 
    }

    static async Task AsyncStart()
    {
        Console.Out.WriteLine("AsyncStart"); 
        return;
    }

    static void Main(string[] args)
    {

        Task t3 = AsyncStart().ContinueWith((ant) => { Continue(); });

        Console.Out.WriteLine("BEFORE"); 
        Task.WhenAny(new Task[] { t3 });
        Console.Out.WriteLine("AFTER");
     }
 }

The output is

AsyncStart
BEFORE
AFTER
Press any key to continue . . .

Continuation is not running!!!!

Yes, I understand the AsyncStart does not contain any await (CS1998), but I still expect t3 to run the continuation. I am missing something very basic

Upvotes: 3

Views: 187

Answers (2)

NeddySpaghetti
NeddySpaghetti

Reputation: 13495

Task.WhenAny returns a Task which you either need to await in which case you'll need to do in in an async method (Main can't be marked as async). Alternatively because you are in a console app you can call Task.WaitAll and that should wait for the continuation to complete. In a GUI app WaitAll can cause a deadlock, but in a console app it is ok.

static void Main(string[] args)
{

   Task t3 = AsyncStart().ContinueWith((ant) => { Continue(); });

   Console.Out.WriteLine("BEFORE"); 
   Task.WaitAll(new Task[] { t3 });
   Console.Out.WriteLine("AFTER");
}

Upvotes: 1

Matt Smith
Matt Smith

Reputation: 17444

Your process ended before the continuation (which runs on a background thread) had the chance to run.

Upvotes: 8

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