线程执行N次后，进程执行M次，如此循环S次

最新推荐文章于 2024-12-05 00:10:24 发布

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本文介绍了一个使用C语言和POSIX线程库实现的线程同步案例，演示了如何利用互斥锁和条件变量来协调两个线程的运行顺序，确保主线程和子线程交替打印特定字符。

#include <stdio.h>
#include <pthread.h>

#define LOOP_S 10
#define PRT_M  2
#define PRT_N  1

int g_flag = 0;

pthread_mutex_t g_lock = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t  g_cond = PTHREAD_COND_INITIALIZER;

void *thread_func(void *arg)
{
	int i, j;
	for (i = 0; i < LOOP_S; ++i)
	{
		pthread_mutex_lock(&g_lock);
		while (g_flag > PRT_N - 1 || g_flag < 0)
			pthread_cond_wait(&g_cond, &g_lock);
		
		for (j = 0; j < PRT_N; ++j)
		{
			printf("%c", 'N');
			++g_flag;
		}

		pthread_mutex_unlock(&g_lock);
		pthread_cond_signal(&g_cond);
	}
}

int main()
{
	pthread_t pid;
	pthread_create(&pid, NULL, thread_func, NULL);

	int i, j;
	for (i = 0; i < LOOP_S; ++i)
	{
		pthread_mutex_lock(&g_lock);
		while (0 <= g_flag && g_flag < PRT_N)
			pthread_cond_wait(&g_cond, &g_lock);
		
		for (j = 0; j < PRT_M; ++j)
			printf("%c", 'M');

		g_flag = 0;
		pthread_mutex_unlock(&g_lock);
		pthread_cond_signal(&g_cond);
	}

	printf("\n");
	pthread_join(pid, NULL);
}