using System;

using System.Threading;

using System.Threading.Tasks;

using System.Linq;

​

public static class Program

{

    public static void Main()

    {

        CancellationTokenSource cts = new CancellationTokenSource(1000);

        cts.Token.Register(() => Console.WriteLine("--Token Canceled"));

        try

        {

            Enumerable.Range(1, 20)

                .AsParallel()

                .WithDegreeOfParallelism(2)

                .WithCancellation(cts.Token)

                .ForAll2(x =>

                {

                    Console.WriteLine($"Processing item #{x}");

                    Thread.Sleep(200);

                });

            Console.WriteLine($"The query was completed successfully");

        }

        catch (OperationCanceledException)

        {

            Console.WriteLine($"The query was canceled");

        }

    }

​

    /// <summary>

    /// Invokes in parallel the specified action for each element in the source,

    /// checking the associated CancellationToken before invoking the action.

    /// </summary>

    public static void ForAll2<TSource>(this ParallelQuery<TSource> source,

        Action<TSource> action)

    {

        foreach (var _ in source.Select(item => { action(item); return 0; })) { }

    }

}