【系统编程】线程同步

 1 #include<stdio.h>
 2 #include<string.h>
 3 #include<pthread.h>
 4 #include<stdlib.h>
 5 #include<unistd.h>
 6 
 7 pthread_mutex_t mutex; //定义一把互斥锁 ，可以想象为 int mutex=1
 8 void *tfn(void *arg){
 9     srand(time(NULL));
10     while(1){
11         pthread_mutex_lock(&mutex); //加锁 ，想象为 mutex-- 
12         printf("hello ");
13         sleep(rand()%3);
14         printf("world\n");
15         pthread_mutex_unlock(&mutex); //解锁，想象为 mutex++
16         sleep(rand()%3);
17     }
18     return NULL;
19 }
20 
21 int main(void){
22     pthread_t tid;
23     srand(time(NULL));
24 
25     int ret = pthread_mutex_init(&mutex,NULL);  //初始化互斥锁
26 
27     pthread_create(&tid,NULL,tfn,NULL);
28     while(1){
29         pthread_mutex_lock(&mutex); //加锁
30         printf("HELLO ");
31         sleep(rand()%3);
32         printf("WORLD\n");
33         pthread_mutex_unlock(&mutex);//解锁
34         sleep(rand()%3);
35 
36     }
37     pthread_join(tid,NULL);
38     return 0;
39 }