Declaring a Task Property and awaiting it

Question

I'm stuck in something I thought so simple that it drives me out of myself.

I need to declare a Task in some point and run it later, I thought of:

Task T1 { get; set; }

public async Task CreateAndAwaitAsync()
{
    T1 = new Task(() => {
        // time consuming work like:
        System.Threading.Thread.Sleep(1000);
    }

    await T1;
}

Of course the body of the lambda AND the method are just for the sake of this example (as I said I need to run it later), but no matter what, with await T1 I just cannot make it into the lambda! What am I missing?? I feel stupid because I have been using the async-await paradigm for quite the few years already that I didn't even imagine this wouldn't work!

Answer 1

I thought it can be answered in comment but better to provide more info.

await means "wait for this task to complete, then do the rest stuff". Task from your example is not started. await will not start it for you, so the whole method will just stuck at await until you start the task.

Even with your current code, if you later do T1.Start() - it will run your lambda and after it is completed - your task returned by CreateAndAwaitAsync will also complete.

Otherwise - either start task right when creating it (Task.Run) or just return Task directly without any async\await:

public Task CreateAndAwaitAsync()
{
    T1 = new Task(() => {
        // time consuming work like:
        System.Threading.Thread.Sleep(1000);
    }
    // if you need to start it somewhere, do T1.Start();
    return T1;
}