主线程等待子线程执行实例一

如果子线程数量有限，可以使用WaitHandle里的 WaitHandle.WaitAll（）方法进行处理，但该WaitHandle 最大支持64个线程处理。

实例代码如下：（参照MSDN）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace AppTest
{
   public class ThreadPoolDemo
    {

       public static readonly ThreadPoolDemo Instance = new ThreadPoolDemo();

       Random r = new Random();

       /// <summary>
       /// 主线程等待所有子线程执行完毕demo
       /// </summary>
       public void MainThreadWaitAllSonThreadFinshed()
       {
           WaitHandle[] waitHandles = new WaitHandle[]{
                new AutoResetEvent(false),
                new AutoResetEvent(false)
            };

           // Queue up two tasks on two different threads;
           // wait until all tasks are completed.
           DateTime dt = DateTime.Now;
           Console.WriteLine("Main thread is waiting for BOTH tasks to complete.");
           ThreadPool.QueueUserWorkItem(new WaitCallback(DoTask), waitHandles[0]);
           ThreadPool.QueueUserWorkItem(new WaitCallback(DoTask), waitHandles[1]);
           //等待所有线程执行完毕
           WaitHandle.WaitAll(waitHandles);
           // The time shown below should match the longest task.
           Console.WriteLine("Both tasks are completed (time waited={0})",
               (DateTime.Now - dt).TotalMilliseconds);

           // Queue up two tasks on two different threads;
           // wait until any tasks are completed.
           dt = DateTime.Now;
           Console.WriteLine();
           Console.WriteLine("The main thread is waiting for either task to complete.");
           ThreadPool.QueueUserWorkItem(new WaitCallback(DoTask), waitHandles[0]);
           ThreadPool.QueueUserWorkItem(new WaitCallback(DoTask), waitHandles[1]);
           //等待任一个线程执行完毕
           int index = WaitHandle.WaitAny(waitHandles);
           // The time shown below should match the shortest task.
           Console.WriteLine("Task {0} finished first (time waited={1}).",
               index + 1, (DateTime.Now - dt).TotalMilliseconds);
       }
       /// <summary>
       /// 执行的工作任务
       /// </summary>
       public void DoTask(object state)
       {
           AutoResetEvent are = (AutoResetEvent)state;
           int time = 1000 * r.Next(2, 10);
           Console.WriteLine("Performing a task for {0} milliseconds.", time);
           Thread.Sleep(time);
           are.Set();
       }

    }