MFC---多线程(线程死锁)

死锁是指多个线程因竞争资源而造成的一种僵局（互相等待），若无外力作用，这些进程都将无法向前推进。

#include <stdio.h>
#include <windows.h>
#include <process.h> 


int iTickets = 5000;
CRITICAL_SECTION g_csA;
CRITICAL_SECTION g_csB;

// A窗口     B窗口

DWORD WINAPI SellTicketA(void* lpParam)
{
	while (1)
	{
		EnterCriticalSection(&g_csA);//进入临界区A
		Sleep(1);
		EnterCriticalSection(&g_csB);//进入临界区B
		if (iTickets > 0)
		{
			Sleep(1);
			iTickets--;
			printf("A remain %d\n", iTickets);
			LeaveCriticalSection(&g_csB);//离开临界区B
			LeaveCriticalSection(&g_csA);//离开临界区A
		}
		else
		{
			LeaveCriticalSection(&g_csB);//离开临界区B
			LeaveCriticalSection(&g_csA);//离开临界区A
			break;
		}
	}
	return 0;
}

DWORD WINAPI SellTicketB(void* lpParam)
{
	while (1)
	{
		EnterCriticalSection(&g_csB);//进入临界区B
		Sleep(1);
		EnterCriticalSection(&g_csA);//进入临界区A
		if (iTickets > 0)
		{
			Sleep(1);
			iTickets--;
			printf("B remain %d\n", iTickets);
			LeaveCriticalSection(&g_csA);//离开临界区A
			LeaveCriticalSection(&g_csB);//离开临界区B
		}
		else
		{
			LeaveCriticalSection(&g_csA);//离开临界区A
			LeaveCriticalSection(&g_csB);//离开临界区B
			break;
		}
	}
	return 0;
}


int main()
{
	HANDLE hThreadA, hThreadB;
	hThreadA = CreateThread(NULL, 0, SellTicketA, NULL, 0, NULL);  //2
	hThreadB = CreateThread(NULL, 0, SellTicketB, NULL, 0, NULL);  //2
	CloseHandle(hThreadA); //1
	CloseHandle(hThreadB); //1
	InitializeCriticalSection(&g_csA); //初始化关键代码段A
	InitializeCriticalSection(&g_csB); //初始化关键代码段B
	Sleep(40000);
	DeleteCriticalSection(&g_csA);//删除临界区
	DeleteCriticalSection(&g_csB);//删除临界区
	system("pause");

	return 0;
}