using System;

using System.Threading;

​

public class Fibonacci

{

    private int _n;

    private int _fibOfN;

    private ManualResetEvent _doneEvent;

​

    public int N { get { return _n; } }

    public int FibOfN { get { return _fibOfN; } }

​

    // Constructor. 

    public Fibonacci(int n, ManualResetEvent doneEvent)

    {

        _n = n;

        _doneEvent = doneEvent;

    }

​

    // Wrapper method for use with thread pool. 

    public void ThreadPoolCallback(Object threadContext)

    {

        int threadIndex = (int)threadContext;

        Console.WriteLine("thread {0} started...", threadIndex);

        _fibOfN = Calculate(_n);

        Console.WriteLine("thread {0} result calculated...", threadIndex);

        _doneEvent.Set();

    }

​

    // Recursive method that calculates the Nth Fibonacci number. 

    public int Calculate(int n)

    {

        if (n <= 1)

        {

            return n;

        }

​

        return Calculate(n - 1) + Calculate(n - 2);

    }

}

​

public class ThreadPoolExample

{

    public static void Main()

    {

        Console.WriteLine(DateTime.Now.DayOfWeek.ToString());

        const int FibonacciCalculations = 10;

​

        // One event is used for each Fibonacci object.

        ManualResetEvent[] doneEvents = new ManualResetEvent[FibonacciCalculations];

        Fibonacci[] fibArray = new Fibonacci[FibonacciCalculations];

        Random r = new Random();

​

        // Configure and start threads using ThreadPool.

        Console.WriteLine("launching {0} tasks...", FibonacciCalculations);

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

        {

            doneEvents[i] = new ManualResetEvent(false);

            Fibonacci f = new Fibonacci(r.Next(20, 40), doneEvents[i]);

            fibArray[i] = f;

            ThreadPool.QueueUserWorkItem(f.ThreadPoolCallback, i);

        }

​

        // Wait for all threads in pool to calculate.

        WaitHandle.WaitAll(doneEvents);

        Console.WriteLine("All calculations are complete.");

​

        // Display the results. 

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

        {

            Fibonacci f = fibArray[i];

            Console.WriteLine("Fibonacci({0}) = {1}", f.N, f.FibOfN);

        }

    }

}