关于线程池的问题，求助！

[xinuaile]

关于线程池的问题，求助！ 注释掉Thread.Sleep(1000);后有时显示hello，有时无，

为什么？ 为什么生成对象可以static AutoResetEvent Event1 = new AutoResetEvent(false); static加在类前面？

using System;
using System.Threading;
public class Example {
public static void Main() {
// Queue the task.
ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc));

Console.WriteLine("Main thread does some work, then sleeps.");

// Thread.Sleep(1000);

Console.WriteLine("Main thread exits.");
}

// This thread procedure performs the task.
static void ThreadProc(Object stateInfo) {

Console.WriteLine("Hello from the thread pool.");
}
}
==============================
//为什么执行完 if (W2K)就跳转到Beta(Object state)的Console.WriteLine方法了?我使用了F11跟踪了半天，也没有看明白，请讲述工作原理！

using System;
using System.Collections;
using System.Threading;
namespace Test
{
//这是用来保存信息的数据结构，将作为参数被传递
public class SomeState

{
public int Cookie;
public SomeState(int iCookie)
{
Cookie = iCookie;
}
}

public class Alpha

{
public Hashtable HashCount;
public ManualResetEvent eventX;
public static int iCount = 0;
public static int iMaxCount = 0;
public Alpha(int MaxCount)
{
HashCount = new Hashtable(MaxCount);
iMaxCount = MaxCount;
}

// 线程池里的线程将调用Beta()方法
public void Beta(Object state)
{
///输出当前线程的hash编码值和Cookie的值
Console.WriteLine(" {0} {1} :", Thread.CurrentThread.GetHashCode(),
((SomeState)state).Cookie);
Console.WriteLine("HashCount.Count=={0}, Thread.CurrentThread.GetHashCode()=={1}", HashCount.Count, Thread.CurrentThread.GetHashCode());
lock (HashCount)

{
// 如果当前的Hash表中没有当前线程的Hash值，则添加之
if (!HashCount.ContainsKey(Thread.CurrentThread.GetHashCode()))
HashCount.Add (Thread.CurrentThread.GetHashCode(), 0);
HashCount[Thread.CurrentThread.GetHashCode()] =
((int)HashCount[Thread.CurrentThread.GetHashCode()])+1;
}

int iX = 2000;
Thread.Sleep(iX);
//Interlocked.Increment()操作是一个原子操作，具体请看下面说明
Interlocked.Increment(ref iCount);
if (iCount == iMaxCount)

{
Console.WriteLine();
Console.WriteLine("Setting eventX ");
eventX.Set();
}
}
}

public class SimplePool

{
public static int Main(string[] args)
{
Console.WriteLine("Thread Pool Sample:");
bool W2K = false;
int MaxCount = 10;//允许线程池中运行最多10个线程
//新建ManualResetEvent对象并且初始化为无信号状态
ManualResetEvent eventX = new ManualResetEvent(false);
Console.WriteLine("Queuing {0} items to Thread Pool", MaxCount);
Alpha oAlpha = new Alpha(MaxCount); // 创建工作项
//注意初始化oAlpha对象的eventX属性
oAlpha.eventX = eventX;
Console.WriteLine("Queue to Thread Pool 0");
try

{
// 将工作项装入线程池
// 这里要用到Windows 2000以上版本才有的API，所以可能出现NotSupportException异常

ThreadPool.QueueUserWorkItem(new WaitCallback(oAlpha.Beta),
new SomeState(0));
W2K = true;
}

catch (NotSupportedException)

{
Console.WriteLine("These API's may fail when called on a non-Windows 2000 system.");
W2K = false;
}
if (W2K)//如果当前系统支持ThreadPool的方法.

{
for (int iItem=1;iItem < MaxCount;iItem++)
{
//插入队列元素
Console.WriteLine("Queue to Thread Pool {0}", iItem);
ThreadPool.QueueUserWorkItem(new WaitCallback(oAlpha.Beta),new SomeState(iItem));
}
Console.WriteLine("Waiting for Thread Pool to drain");
// 等待事件的完成，即线程调用ManualResetEvent.Set()方法
eventX.WaitOne(Timeout.Infinite,true);
// WaitOne()方法使调用它的线程等待直到eventX.Set()方法被调用
Console.WriteLine("Thread Pool has been drained (Event fired)");
Console.WriteLine();
Console.WriteLine("Load across threads");
foreach(object o in oAlpha.HashCount.Keys)
Console.WriteLine("{0} {1}", o, oAlpha.HashCount[o]);
}
Console.ReadLine();
return 0;

}
}
}

[elite2018]

If you comment out the Sleep, the main thread exits before
the thread pool task runs. The thread pool uses background
threads, which do not keep the application running.