[windows]_[线程同步的方法]

windows下一般有四种线程同步的方法：

（1）事件

（2）信号量

（3）互斥量

（4）临界区

下面将展示各自的用法

（1）事件

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

int g = 0;
HANDLE events;

DWORD WINAPI ThreadFun1(PVOID pParam)
{
	while (g < 100)
	{
		WaitForSingleObject(events, INFINITE);
		g++;
		printf("Thread1:%d\n", g);
		SetEvent(events);
	}
	return 0;
}

DWORD WINAPI ThreadFun2(PVOID pParam)
{
	while (g < 100)
	{
		WaitForSingleObject(events, INFINITE);
		g++;
		printf("Thread2:%d\n", g);
		SetEvent(events);
	}
	return 0;
}

int main()
{
	HANDLE hand1 = CreateThread(NULL, 0, ThreadFun1, NULL, 0, NULL);
	HANDLE hand2 = CreateThread(NULL, 0, ThreadFun2, NULL, 0, NULL);
	events = CreateEvent(NULL, FALSE, FALSE, NULL);
	SetEvent(events);
	char ch = getchar();
	return 0;
}

输出结果：

（2）信号量

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

int g = 0;
HANDLE sema;

DWORD WINAPI ThreadFun1(PVOID pParam)
{
	while (g < 100)
	{
		WaitForSingleObject(sema, INFINITE);
		g++;
		printf("Thread1:%d\n", g);
		ReleaseSemaphore(sema, 1, NULL);
	}
	return 0;
}

DWORD WINAPI ThreadFun2(PVOID pParam)
{
	while (g < 100)
	{
		WaitForSingleObject(sema, INFINITE);
		g++;
		printf("Thread2:%d\n", g);
		ReleaseSemaphore(sema, 1, NULL);
	}
	return 0;
}

int main()
{
	HANDLE hand1 = CreateThread(NULL, 0, ThreadFun1, NULL, 0, NULL);
	HANDLE hand2 = CreateThread(NULL, 0, ThreadFun2, NULL, 0, NULL);
	sema = CreateSemaphore(NULL, 1, 1, NULL);
	char ch = getchar();
	return 0;
}

输出结果：

（3）互斥量

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

int g = 0;
HANDLE Mutex;

DWORD WINAPI ThreadFun1(PVOID pParam)
{
	while (g < 100)
	{
		WaitForSingleObject(Mutex, INFINITE);
		g++;
		printf("Thread1:%d\n", g);
		ReleaseMutex(Mutex);
	}
	return 0;
}

DWORD WINAPI ThreadFun2(PVOID pParam)
{
	while (g < 100)
	{
		WaitForSingleObject(Mutex, INFINITE);
		g++;
		printf("Thread2:%d\n", g);
		ReleaseMutex(Mutex);
	}
	return 0;
}

int main()
{
	HANDLE hand1 = CreateThread(NULL, 0, ThreadFun1, NULL, 0, NULL);
	HANDLE hand2 = CreateThread(NULL, 0, ThreadFun2, NULL, 0, NULL);
	Mutex = CreateMutex(NULL, FALSE, NULL);
	char ch = getchar();
	return 0;
}

输出结果:

（4）临界区

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

int g = 0;
CRITICAL_SECTION g_cs;

DWORD WINAPI ThreadFun1(PVOID pParam)
{
	while (g < 100)
	{
		EnterCriticalSection(&g_cs);
		g++;
		printf("Thread1:%d\n", g);
		LeaveCriticalSection(&g_cs);
	}
	return 0;
}

DWORD WINAPI ThreadFun2(PVOID pParam)
{
	while (g < 100)
	{
		EnterCriticalSection(&g_cs);
		g++;
		printf("Thread2:%d\n", g);
		LeaveCriticalSection(&g_cs);
	}
	return 0;
}

int main()
{
	HANDLE hand1 = CreateThread(NULL, 0, ThreadFun1, NULL, 0, NULL);
	HANDLE hand2 = CreateThread(NULL, 0, ThreadFun2, NULL, 0, NULL);
	InitializeCriticalSection(&g_cs);
	char ch = getchar();
	return 0;
}

输出结果：

总结：四种方法中只有临界区未达到预期的效果。