Having read a /lot/ of documentation on the async await pattern I thought I had a pretty good handle on the pattern. I read all about async all the way then read another article that mentions ‘if it runs in under 50 milliseconds don’t async it’. It seems there is conflicting information and/or opinions and I have managed to just confuse myself. I have also read that Task.Yield() will force an async decorated method to run asynchronously.
Given the following code:
static async Task MethodA() {
await MethodB().ConfigureAwait(false);
}
static async Task MethodB() {
await Task.Yield();
MethodC();
}
static void MethodC() {
// do some synchronous stuff
}
static async Task Main(string[] args) {
var task1 = Task.Run(() => MethodA().ConfigureAwait(false));
var task2 = Task.Run(() => MethodB().ConfigureAwait(false));
await Task.WhenAll(new List<Task>() { task1, task2 });
}
Will MethodC run synchronously or asynchronously, I assumed asynchronously as it was called from an asynchronous method. Also, is Task.Yield necessary at all?
To be honest this is doing my head in, every article I have read delves deeper and deeper into the async await pattern with the whys and wherefores and is just adding more complexity to the question. Just looking for a simple answer.
>Solution :
Will MethodC run synchronously or asynchronously
Synchronously. It has a synchronous signature, so it will always run synchronously.
I assumed asynchronously as it was called from an asynchronous method
The context from which it is called is irrelevant to how MethodC will run.
is Task.Yield necessary at all
Well it will force MethodB to yield a Task before MethodC runs, but this will be incomplete until MethodC finishes, and because MethodC is synchronous (does not release the thread) it achieves nothing useful.
Just looking for a simple answer
async bubbles up the call stack, and because you are not consuming an async method here (MethodC is synchronous) you should not be using async at all.