用C#线程池编程实现斐波那契数列

//Copyright (C) Microsoft Corporation.  All rights reserved.

using System;
using System.Threading;

// 以下的斐波那契类为使用一个辅助线程执行费时的Fibonacci(N)计算提供一个接口.
// N 传递给Fibonacci类成员变量初始化, 和指示操作结束的事件对象.
// 数列结果可以通过FibOfN属性提取.
public class Fibonacci
{
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();
}

// 递归算法计算Nth Fibonacci数列.
public int Calculate(int n)
{
if (n <= 1)
{
return n;
}
else
{
return Calculate(n - 1) + Calculate(n - 2);
}
}

public int N { get { return _n; } }
private int _n;

public int FibOfN { get { return _fibOfN; } }
private int _fibOfN;

ManualResetEvent _doneEvent;
}

public class ThreadPoolExample
{
static void Main()
{
const int FibonacciCalculations = 10;

// 每一个对象初始化一个事件
ManualResetEvent[] doneEvents = new ManualResetEvent[FibonacciCalculations];
Fibonacci[] fibArray = new Fibonacci[FibonacciCalculations];
Random r = new Random();

// 用线程池方式启动线程:
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);
}

// 等待所有在池中的线程计算...
WaitHandle.WaitAll(doneEvents);
Console.WriteLine("Calculations complete.");

// 显示结果...
for (int i= 0; i<FibonacciCalculations; i++)
{
Fibonacci f = fibArray[i];
Console.WriteLine("Fibonacci({0}) = {1}", f.N, f.FibOfN);
}
}
}

以上代码在VisualStudio2008环境下运行调试。