Windows线程（五）关键段无法解决线程同步问题

关键段：

关键段类型CRITICAL_SECTION

1.初始化关键段：
void InitializeCriticalSection(LPCRITICAL_SECTION lpCriticalSection);
2.销毁关键段：
void DeleleCriticalSection(LPCRITICAL_SECTION lpCriticalSection);
3.进入关键段：
void EnterCriticalSection(LPCRITICAL_SECTION lpCriticalSection);
4.离开关键段：
void LeaveCriticalSection(LPCRITICAL_SECTION lpCriticalSection);

关键段解决线程互斥问题测试代码如下：

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

#define THREAD_NUM 10

CRITICAL_SECTION g_csThreadParameter;
CRITICAL_SECTION g_csThreadCode;

unsigned long g_nNum;

unsigned int __stdcall ThreadFun(void *pM)
{
int nThreadNum = *(int *)pM;

//离开子线程的关键区域
LeaveCriticalSection(&g_csThreadParameter);
Sleep(50);

//进入子线程互斥区域
EnterCriticalSection(&g_csThreadCode);
g_nNum++;

Sleep(0);

printf("线程编号为%d, 全局资源值为%d\n", nThreadNum, g_nNum);

//离开各自线程互斥区域
LeaveCriticalSection(&g_csThreadCode);

return 0;
}

int main(int argc, char *argv[])
{
HANDLE handle[THREAD_NUM];
int i = 0;

printf("--------------------经典线程同步：关键段--------------------\n");

//初始化关键段
InitializeCriticalSection(&g_csThreadParameter);
InitializeCriticalSection(&g_csThreadCode);

g_nNum = 0;

while(i < THREAD_NUM)
{
//进入子线程关键段区域
EnterCriticalSection(&g_csThreadParameter);
handle[i] = (HANDLE)_beginthreadex(NULL, 0, ThreadFun, &i, 0, NULL);
++i;
}

WaitForMultipleObjects(THREAD_NUM, handle, 1, INFINITE);

//删除关键段
DeleteCriticalSection(&g_csThreadCode);
DeleteCriticalSection(&g_csThreadParameter);

system("pause");

return 0;
}

以上代码在Visual Studio 2010中的5次运行结果如下：











如上图所示，该段使用关键段的测试代码的确解决了线程互斥的问题，但是并没有解决线程同步的问题，因此我们需要其他方法，解决线程同步问题。