using System;

public class Program

{

    private static async Task Main(string[] args)

    {

        Console.WriteLine("=== START MAIN ===");

​

        var ms = new int[] { 1, 2, 3, 4, 5 };

​

        var tasks = new Task[ms.Length];

​

        for (int i = 0; i < ms.Length; i++)

        {

            Console.WriteLine($"{i}: {ms[i]}");

​

            tasks[i] = Task.Run(() => Handle(ms[i]));

        }

​

        await Task.WhenAll(tasks);

​

        Console.WriteLine("=== END MAIN ===");

    }

​

    static void Handle(int userId)

    {

        Console.WriteLine($"--> Handle {userId}");

​

        Thread.Sleep(3000);

    }

}