多线程同步

 1 #include <stdio.h>
 2 #include <pthread.h>
 3 #include <string.h>  
 4 
 5 
 6 pthread_t thread[2];
 7 int number = 0;  
 8 pthread_mutex_t mut; 
 9 
10 
11 void studentA()
12 {
13     int i;
14     for(i=0;i<5;i++)
15     {  
16         pthread_mutex_lock(&mut);
17         //扫地
18         number++;
19         if( number>=5 )
20             printf("student A has finish his work! \n"); 
21         
22         pthread_mutex_unlock(&mut);    
23         //休息1秒钟
24         sleep(1);
25     } 
26     //退出 
27     pthread_exit(NULL);
28 }
29 
30 void studentB()
31 {        
32     while(1)
33     {  
34         pthread_mutex_lock(&mut);
35         if(number>=5)    //判断A同学是否已经扫完5次地
36         {   
37             //执行拖地
38             number = 0; 
39             printf("student B has finish his work \n");
40             
41             pthread_mutex_unlock(&mut);
42             //退出
43             break;        
44         } 
45         else
46         {  
47             pthread_mutex_unlock(&mut);
48             //睡眠2秒钟
49             sleep(2);    
50         }    
51     }
52     pthread_exit(NULL);  //退出
53 }
54 
55 int main()
56 {   
57     //初始化互斥锁
58     pthread_mutex_init(&mut,NULL);
59 
60     //创建A同学线程
61     pthread_create(&thread[0],NULL,studentA,NULL);
62     
63     //创建B同学线程
64     pthread_create(&thread[1],NULL,studentB,NULL);
65         
66     //等待A同学线程结束
67     pthread_join(thread[0],NULL);
68     
69     //等待B同学线程结束
70     pthread_join(thread[1],NULL);
71         
72     return 0;
73 }

 1 #include <stdio.h>
 2 #include <pthread.h>
 3 #include <string.h>  
 4 
 5 
 6 pthread_t thread[2];
 7 int number = 0;  
 8 pthread_mutex_t mut; 
 9 pthread_cond_t cond_ready=PTHREAD_COND_INITIALIZER;
10 
11 void studentA()
12 {
13     int i;
14     for(i=0;i<5;i++)
15     {  
16         pthread_mutex_lock(&mut);
17         //扫地
18         number++;
19         if( number>=5 )
20         {
21             printf("student A has finish his work! \n"); 
22             
23             //通知B同学
24             pthread_cond_signal(&cond_ready);  
25         }    
26         pthread_mutex_unlock(&mut);    
27         //休息1秒钟
28         sleep(1);
29     } 
30     //退出 
31     pthread_exit(NULL);
32 }
33 
34 void studentB()
35 {        
36 
37     pthread_mutex_lock(&mut);
38     if(number<5)
39         pthread_cond_wait(&cond_ready, &mut);    
40     number = 0;  
41     pthread_mutex_unlock(&mut);
42     printf("student B has finish his work! \n"); 
43     
44     pthread_exit(NULL);  //退出
45 }
46 
47 int main()
48 {   
49     //初始化互斥锁
50     pthread_mutex_init(&mut,NULL);
51 
52     //创建A同学线程
53     pthread_create(&thread[0],NULL,studentA,NULL);
54     
55     //创建B同学线程
56     pthread_create(&thread[1],NULL,studentB,NULL);
57         
58     //等待A同学线程结束
59     pthread_join(thread[0],NULL);
60     
61     //等待B同学线程结束
62     pthread_join(thread[1],NULL);
63         
64     return 0;
65 }