multiple parallel async calls with await

Question

As far as I know, when runtime comes across the statement below it wraps the rest of the function as a callback to the method which is invoked asynchronously (someCall() in this example). In this case anotherCall() will be executed as a callback to someCall():

    await someCall();
    await anotherCall();

I wonder if it is possible to make runtime perform like this: call someCall() in async fashion and return immediately to the calling thread, then invoke anotherCall() similarly (without waiting someCall to complete). Because I need these two methods to run asynchronously and suppose these calls are just fire and forget calls.

Is it possible to implement this scenario using just async and await (not using old begin/end mechanism)?

Answer 1

The async/await includes a few operators to help with parallel composition, such as WhenAll and WhenAny.

var taskA = someCall(); // Note: no await
var taskB = anotherCall(); // Note: no await

// Wait for both tasks to complete.
await Task.WhenAll(taskA, taskB);

// Retrieve the results.
var resultA = taskA.Result;
var resultB = taskB.Result;