CreateMutex WaitForSingleObject ReleaseMutex使用「建议收藏」

大家好，又见面了，我是你们的朋友全栈君。

HANDLE CreateMutex(

 LPSECURITY_ATTRIBUTES lpMutexAttributes,//

 BOOL bInitialOwner,  // flag for initial ownership

 LPCTSTR lpName     // pointer to mutex-object name

 );

参数2：指示互斥对象的初始拥有者。 如果该值是真,调用者创建互斥对象,调用的线程获得互斥对象的所有权。 否则,不拥有所有权,此时互斥对象处于空闲状态,其他线程可以占用。

(-)  主线程中创建拥有所有权的互斥量,两个子线程中分别等待互斥量-》没有输出

DWORD WINAPI ThreadProc1(LPVOID lpParameter);
DWORD WINAPI ThreadProc2(LPVOID lpParameter);

int    ticket = 50;
HANDLE hMutex = NULL;

int _tmain(int argc, _TCHAR* argv[])
{
	HANDLE handle1 = CreateThread(NULL,0,ThreadProc1,NULL,0,NULL);
	HANDLE handle2 = CreateThread(NULL,0,ThreadProc2,NULL,0,NULL);

	CloseHandle(handle1);
	CloseHandle(handle2);

	hMutex = CreateMutex(NULL,TRUE,NULL); //第二个参数为TRUE,互斥对象的所有权为主线程所有,非空闲状态

	Sleep(4000);

	return 0;
}

DWORD WINAPI ThreadProc1(LPVOID lpParameter)
{

	//WaitForSingleObject(hMutex,INFINITE); //第二个参数为INFINITE表示一直等待，直到拥有互斥对象
	while(TRUE)
	{

		WaitForSingleObject(hMutex,INFINITE); //第二个参数为INFINITE表示一直等待，直到拥有互斥对象

		if ( ticket > 0 )
		{
			Sleep(1);

		    printf("thread1 sale the ticket id is: %d\n", ticket--);
		}
		else
		{
			break;
		}                 

		ReleaseMutex(hMutex); //使用完了，将互斥对象还给操作系统
	}
	//ReleaseMutex(hMutex); //使用完了，将互斥对象还给操作系统
	return 0;
} 

DWORD WINAPI ThreadProc2(LPVOID lpParameter)
{

	while(TRUE)
	{

		WaitForSingleObject(hMutex,INFINITE); //第二个参数为INFINITE表示一直等待，直到拥有互斥对象         

		if ( ticket > 0 )
		{

		   Sleep(1);

		   printf("thread2 sale the ticket id is: %d\n", ticket--);

		}
		else
		{
			break;
		}        

		ReleaseMutex(hMutex); //使用完了，将互斥对象还给操作系统
    }

	return 0;
}

(二)  主线程中创建没有所有权的互斥量,两个子线程中分别等待互斥量-》输出如下

thread1 sale the ticket id is: 50
thread2 sale the ticket id is: 49
thread1 sale the ticket id is: 48
thread2 sale the ticket id is: 47
thread1 sale the ticket id is: 46
thread2 sale the ticket id is: 45
thread1 sale the ticket id is: 44
thread2 sale the ticket id is: 43
thread1 sale the ticket id is: 42
thread2 sale the ticket id is: 41
thread1 sale the ticket id is: 40
thread2 sale the ticket id is: 39
thread1 sale the ticket id is: 38
thread2 sale the ticket id is: 37
thread1 sale the ticket id is: 36
thread2 sale the ticket id is: 35
thread1 sale the ticket id is: 34
thread2 sale the ticket id is: 33
thread1 sale the ticket id is: 32
thread2 sale the ticket id is: 31
thread1 sale the ticket id is: 30
thread2 sale the ticket id is: 29
thread1 sale the ticket id is: 28
thread2 sale the ticket id is: 27
thread1 sale the ticket id is: 26
thread2 sale the ticket id is: 25
thread1 sale the ticket id is: 24
thread2 sale the ticket id is: 23
thread1 sale the ticket id is: 22
thread2 sale the ticket id is: 21
thread1 sale the ticket id is: 20
thread2 sale the ticket id is: 19
thread1 sale the ticket id is: 18
thread2 sale the ticket id is: 17
thread1 sale the ticket id is: 16
thread2 sale the ticket id is: 15
thread1 sale the ticket id is: 14
thread2 sale the ticket id is: 13
thread1 sale the ticket id is: 12
thread2 sale the ticket id is: 11
thread1 sale the ticket id is: 10
thread2 sale the ticket id is: 9
thread1 sale the ticket id is: 8
thread2 sale the ticket id is: 7
thread1 sale the ticket id is: 6
thread2 sale the ticket id is: 5
thread1 sale the ticket id is: 4
thread2 sale the ticket id is: 3
thread1 sale the ticket id is: 2
thread2 sale the ticket id is: 1

(三)  主线程中创建没有所有权的互斥量,主线程和子线程中分别等待互斥量-》主线程和子线程交替输出

(四)  主线程中创建拥有所有权的互斥量,主线程和子线程中分别等待互斥量-》只有主线程输出

这个原因不知道如何解释，难道在主线程中创建有所有权的,其他线程就永远等待不到了吗

(五) 子线程中创建拥有所有权的互斥量,主线程和子线程中分别等待互斥量-》只有子线程输出

(四)和(五)的结果可以说明在哪个线程中创建拥有所有权的互斥量,所有权永远被此线程占有，即使释放了互斥量。

以上结果都在Wince6.0测试。

后来找到一个 说明，貌似可以说明以上结论呢：

如创建进程希望立即拥有互斥体，则设为TRUE。一个互斥体同时只能由一个线程拥有。是FALSE，表示刚刚创建的这个Mutex不属于任何线程 也就是没有任何线程拥有他，一个Mutex在没有任何线程拥有他的时候，他是处于激发态的， 所以处于有信号状态。