using System;

using System.Linq;

using System.Threading;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        int[] nums = Enumerable.Range(0, 100000).ToArray();

        CancellationTokenSource cts = new CancellationTokenSource();

​

        // Use ParallelOptions instance to store the CancellationToken

        ParallelOptions po = new ParallelOptions();

        po.CancellationToken = cts.Token;

        po.MaxDegreeOfParallelism = System.Environment.ProcessorCount;

        Console.WriteLine($"ProcessorCount: {System.Environment.ProcessorCount}");

​

        // Run a task so that we can cancel from another thread.

        Task.Factory.StartNew(async () =>

        {

            Console.WriteLine($"Task started {DateTime.Now}");

            await Task.Delay(10);

            cts.Cancel();

            Console.WriteLine($"Task ended {DateTime.Now}");

        });

​

        try

        {

            Console.WriteLine($"Parallel started {DateTime.Now}");

            Parallel.ForEach(nums, po, (num) =>

            {

                double d = Math.Sqrt(num);

                Console.WriteLine($"Sqrt of {num} is {d} on {Thread.CurrentThread.ManagedThreadId}");

            });

            Console.WriteLine($"Parallel ended {DateTime.Now}");

        }

        catch (OperationCanceledException e)

        {

            Console.WriteLine(e.Message);

        }

        finally

        {

            cts.Dispose();

        }

    }

}