TaskRun

using System;
using System.Threading.Tasks;
using System.Collections.Generic;

class Program {
    private void WriteABunchOfStuff(int id){
        int j=0;
        for (int i=0; i<50; i++){
            Console.WriteLine("{0}# task here!", id);
            j++;
        }
    }

    public async Task Run(){
        List<Task> tasks = new();

        for (int i=0; i<10; i++){
            var tmp=i;
            tasks.Add(Task.Run(()=>{WriteABunchOfStuff(tmp); Console.WriteLine("{0} Done", tmp);}));
        }

        await Task.WhenAll(tasks);
        Console.WriteLine("Done");
    }

    public static async Task Main(){
        var p = new Program();
        await p.Run();
    }
}