Linux多线程──主线程和子线程分别循环一定次数

来源：互联网发布：上海u盘数据恢复编辑：程序博客网时间：2024/05/17 07:20

子线程循环 10 次，接着主线程循环 100 次，接着又回到子线程循环 10 次，接着再回到主线程又循环 100 次，如此循环50次，试写出代码。

要注意条件变量的自动复位问题。参看这篇文章：Linux 的多线程编程的高效开发经验

代码：

#include <pthread.h>#include <stdio.h>// 互斥锁，条件变量pthread_mutex_t mutex;pthread_cond_t cond;// 循环次数int main_count = 0;int subthread_count = 0;// 线程等待标志bool main_thread_wait_flag = false;bool subthread_wait_flag = false;void main_thread_func();void *subthread_func(void *arg);int main(int argc, char **argv){    pthread_t tid;    pthread_mutex_init(&mutex, NULL);    pthread_cond_init(&cond, NULL);        pthread_create(&tid, NULL, subthread_func, NULL);    main_thread_func();    pthread_join(tid, NULL);        return 0;}void main_thread_func(){    while (true)    {        pthread_mutex_lock(&mutex);        main_thread_wait_flag = true;        pthread_cond_wait(&cond, &mutex);        main_thread_wait_flag = false;        pthread_mutex_unlock(&mutex);                for (int i = 1; i <= 100; ++i)        {            fprintf(stdout, "main thread: %d\n", i);        }                        while (true)        {            pthread_mutex_lock(&mutex);            if (true == subthread_wait_flag)            {                pthread_cond_signal(&cond);                pthread_mutex_unlock(&mutex);                break;            }            pthread_mutex_unlock(&mutex);        }                ++main_count;        if (main_count >= 50)        {            fprintf(stdout, "main thread loop 50 times\n");            break;        }    }}void *subthread_func(void *arg){    while (true)    {        for (int i = 1; i <= 10; ++i)        {            fprintf(stdout, "subthread: %d\n", i);        }        while (true)        {            pthread_mutex_lock(&mutex);            if (true == main_thread_wait_flag)            {                pthread_cond_signal(&cond);                pthread_mutex_unlock(&mutex);                break;            }            pthread_mutex_unlock(&mutex);        }        pthread_mutex_lock(&mutex);        subthread_wait_flag = true;        pthread_cond_wait(&cond, &mutex);        subthread_wait_flag = false;        pthread_mutex_unlock(&mutex);                ++subthread_count;        if (subthread_count >= 50)        {            fprintf(stdout, "subthread loop 50 times\n");            break;        }    }    return (void *)0;}