Windows线程（五）关键段无法解决线程同步问题

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关键段：

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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);

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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;
}

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以上代码在Visual Studio 2010中的5次运行结果如下：

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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。