I need a little rule about correct usage of await. Run this code in .net core c# 7.2:
static class Program
{
static async Task<string> GetTaskAsync(int timeout)
{
Console.WriteLine("Task Thread: " + Thread.CurrentThread.ManagedThreadId);
await Task.Delay(timeout);
return timeout.ToString();
}
static async Task Main()
{
Console.WriteLine("Main Thread: " + Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("Should be greater than 5000");
await Watch(NotParallel);
Console.WriteLine("Should be less than 5000");
await Watch(Parallel);
}
public static async Task Parallel()
{
var res1 = GetTaskAsync(2000);
var res2 = GetTaskAsync(3000);
Console.WriteLine("result: " + await res1 + await res2);
}
public static async Task NotParallel()
{
var res1 = await GetTaskAsync(2000);
var res2 = await GetTaskAsync(3000);
Console.WriteLine("result: " + res1 + res2);
}
private static async Task Watch(Func<Task> func) {
var sw = new Stopwatch();
sw.Start();
await func?.Invoke();
sw.Stop();
Console.WriteLine("Elapsed: " + sw.ElapsedMilliseconds);
Console.WriteLine("---------------");
}
}
As you all can see the behavior of two methods are different. It's easy to get wrong in practice. So i need a "thumb rule".
Update for real men Please, run code. And explain please why Parallel() runs faster than NonParallel().
Taskis something that may yield a result if youawaitfor it. Until then, it's just an object which does nothing. In yourNonParallelmethod you don't even have a second task until the first one yields, so of course these methods are totally different.