I’ve heard a lot about how a new thread is not created with async awiat. I decided to check what would happen if there was an while(true) in the main function and the asynchronous function.

namespace asyncTest
{
    public class Program
    {

        public static void Task1()
        {
            while (true) {
                Console.WriteLine("Task1: " + Thread.CurrentThread.ManagedThreadId);
                Thread.Sleep(1000);
            }
        }

        public static async void async()
        {
            Console.WriteLine("async start: " + Thread.CurrentThread.ManagedThreadId);
            await Task.Run(Task1);
            Console.WriteLine("async end: " + Thread.CurrentThread.ManagedThreadId);
        }

        static void Main(string[] args)
        {
            async();
            while (true) {
                Console.WriteLine("main: " + Thread.CurrentThread.ManagedThreadId);
                Thread.Sleep(1000);
            }
        }
    }
}

But for some reason my functions are executed in different threads:

I want to understand why they are executed in different threads if async await does not create a thread. And I want to know how high-load operations are performed asynchronously, as in this example. Who performs the asynchronous operation on an additional thread? or are they executed in the same thread?