using System;

using System.Linq;

using System.Threading;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        int numThreads = 0;

​

        Parallel.ForEach(Enumerable.Range(0, 1000), _ =>

        {

            int i = Interlocked.Increment(ref numThreads);

            Console.WriteLine("Current num threads: " + i);

​

            Thread.Sleep(int.MaxValue);

        });

    }

}