using System;

using System.Collections.Concurrent;

using System.Threading;

using System.Threading.Tasks;

using System.Collections.Generic;

​

public class Program

{

    private static BlockingCollection<Task<int>> BlockingCollection {get;set;}  

    public static void Producer(int numTasks)

    {

        Random r = new Random(7);

        for(int i = 0 ; i < numTasks ; i++)

        {

            int closured = i;

            Task<int> task = new Task<int>(()=>

            { 

                Thread.Sleep(r.Next(100));

                Console.WriteLine("Produced: " + closured);

                return closured;

            });

            BlockingCollection.Add(task);

            task.Start();

        }

        BlockingCollection.CompleteAdding();

    }

​

    public static void Main()

    {

        int numTasks = 20;

        int maxParallelism = 3;

​

        BlockingCollection = new BlockingCollection<Task<int>>(maxParallelism);

        Task.Factory.StartNew(()=> Producer(numTasks));

        foreach(var task in BlockingCollection.GetConsumingEnumerable())

        {

            task.Wait();

            Console.WriteLine("              Consumed: "+ task.Result);

            task.Dispose();

        }

    }

}