Await inside System.Threading.Timer callback

Question

I am doing an ASP.NET Web API and have a BackgroundService like this:

Inside Doing, I to await a task 1:

The problem is with the TimeSpan.FromSeconds(0.5)) the ExecuteAsync will do create a new Doing() without waiting for my task to be done.

The console result :

How can I resolve this? Or is there a way to achieve a background task with await for the task completion?

Answer 1

Don't use a Timer. Instead set up a loop and use Task.Delay for the wait period.

protected override async Task ExecuteAsync(CancellationToken cancellationToken)
{
    var delay = TimeSpan.FromSeconds(0.5);
    
    while (!cancellationToken.IsCancellationRequested)
    {                            
        await Doing();
        await Task.Delay(delay, cancellationToken);
    }
}

See an example in Microsofts documentation.