DuplicateHandle 复制的线程句柄，为什么在主线程取不到GetExitCodeThread

[unhappyless]

#include <windows.h>
#include <process.h>
#include <stdio.h>
#include <iostream>
using namespace std;

HANDLE g_Handle =NULL;
unsigned __stdcall thread_func(void* lpParam)
{

	BOOL ret = DuplicateHandle(GetCurrentProcess(),GetCurrentThread(),
		GetCurrentProcess(),&g_Handle,DUPLICATE_SAME_ACCESS,FALSE,0);

	if(!ret)
	{
		cout<<"DuplicateHandle Failed "<<GetLastError()<<endl;
	}
	
	Sleep(10000);
		
		
	return 9;
}



int main()
{
	HANDLE hThread = (HANDLE)_beginthreadex(NULL,0,thread_func,NULL,0,NULL);
	
	CloseHandle(hThread);
	int j = 10;
	while(j--)
	{
		if(g_Handle)
		{
			DWORD code;
			BOOL ret = GetExitCodeThread(g_Handle,&code);
			if(ret)
			{
				cout<<" ExitCode: "<<code<<endl;
			}
			else
			{
				cout<<"GetExitCodeThread return FALSE ErrorCode:"<<GetLastError()<<endl;
			}

		}
		else
		{
			cout<<"g_Handle Is NULL"<<endl;
		}
		Sleep(1000);
	}
	
	cout<<"press any key to continue..."<<endl;
	getchar();

}

我知道主线程创建线程时返回了句柄，用这个句柄可以取到GetExitCodeThread 。但我有个需求就如上代码所示，只能在子线程里操作，我想获得当前线程真实句柄。
看msdn上说GetCurrentThread　获得的是伪句柄，DuplicateHandle　后就获得真实句柄，请教下我是哪用错了

[unhappyless]

顶起来顶起来

[lm_whales]

GetCurrentProcess() 读取，进程句柄，然后读出进程ID然后枚举其中的主线程

[Saleayas]

HANDLE volatile g_Handle =NULL;

[赵4老师]

《Windows核心编程》