IO完成端口+线程池的应用（终于有点明白了，大家帮看下哪里写的不合理

C/C++ code

/ 异步方式调用.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <windows.h>#include <iostream>using namespace std;PTP_WORK hWork = NULL; //定义工作项变量HANDLE hPort;    //定义I/O完成端口句柄HANDLE hFile[4] = {0}; //enum Key{CK_READ1,CK_READ2,CK_READ3,CK_READ4}//线程池处理函数VOID NTAPI WorkCallback(PTP_CALLBACK_INSTANCE Instance,PVOID Context){    DWORD dwNumBytes;    ULONG_PTR CompletionKey;    OVERLAPPED* pOverlapped = NULL;       //不断等待，当有IO请求完成的时候，执行相应的操作    while(1)    {        BOOL bOk = GetQueuedCompletionStatus(hPort,&dwNumBytes,&CompletionKey,&pOverlapped,5000);        DWORD dwError = GetLastError();        cout<<"完成等待"<<endl;        if(bOk)        {            switch(CompletionKey)            {            case 0:                cout<<"文件1"<<endl;                //执行与文件1有关的其他操作，操作完成后，关闭句柄                CloseHandle(hFile[0]);                                break;            case 1:                cout<<"文件2"<<endl;                CloseHandle(hFile[1]);                break;            case 2:                cout<<"文件3"<<endl;                CloseHandle(hFile[2]);                break;            case 3:                cout<<"文件4"<<endl;                CloseHandle(hFile[3]);                break;            default:                cout<<"出现错误"<<endl;                break;            }        }        else        {            if(pOverlapped != NULL)            {                cout<<"pOverlapped != NULL"<<endl;            }            else if(dwError == WAIT_TIMEOUT)            {                cout<<" WAIT_TIMEOUT"<<endl;            }            else            {                cout<<"未知错误"<<endl;            }        }    }    cout<<"处理工作项"<<endl;}//创建新的I/O完成端口函数HANDLE CreateNewCompletionPort(DWORD dwNumberOfConcurrentThreads){    return CreateIoCompletionPort(INVALID_HANDLE_VALUE,NULL,0,dwNumberOfConcurrentThreads);}//设备与I/O完成端口关联函数BOOL AssociateDeviceWithCompletionPort(HANDLE hCompletionPort,HANDLE hDevice,DWORD dwCompletionKey){    HANDLE h = CreateIoCompletionPort(hDevice,hCompletionPort,dwCompletionKey,0);    return (h == hCompletionPort);}int _tmain(int argc, _TCHAR* argv[]){    LPCWSTR pszName[] = {_T("a1.txt"),_T("a2.txt"),_T("a3.txt"),_T("a4.txt")};    OVERLAPPED o = {0};    o.Offset = 0;    BYTE bBuffer[100] =  "abcde";    //打开文件句柄（共4个文件句柄）    for(int i=0; i<4; ++i)    {        hFile[i] = CreateFile(pszName[i],GENERIC_WRITE,0,NULL,OPEN_ALWAYS,FILE_FLAG_OVERLAPPED,NULL);    }    //创建一个I/O完成端口    hPort = CreateNewCompletionPort(0);    //将4个文件句柄与完成端口关联    for(int i=0; i<4;++i)    {        if(!AssociateDeviceWithCompletionPort(hPort,hFile[i],i))        {            cout<<"完成端口关联失败"<<endl;        }    }    if(FALSE == TrySubmitThreadpoolCallback(WorkCallback,NULL,NULL))    {        cout<<"线程池失败"<<endl;    }    //异步模式的4个IO请求，不影响主线程的继续运行    for(int i=0; i<4; ++i)    {        WriteFile(hFile[i],bBuffer,100,NULL,&o);        DWORD dwError = GetLastError();        if(ERROR_IO_PENDING ==dwError)            cout<<"进入了异步"<<endl;                   }        cout<<"继续主线程"<<endl;    for(int i = 0;i<100;++i)    {        cout<<i<<endl;    }    Sleep(5000);    system("pause");    return 0;}

这是根据自己的理解写的，不知道对不对，请指教啊

[解决办法]
把你的代码在实际环境中跑一下看看有什么问题？
------解决方案--------------------

不错啊
异步IO理解有点费力。我现在都还没搞懂