跟我一起做面试题-linux线程编程(2)

如题所述：

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。

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之前编程用到pthread_cond_init没用调用相应destroy，程序执行完毕后也没core掉，在网上找了找原因，最终确定在linux的实现原理。

说白了，linux下可以不调用。但为了健壮性，还是要用配套的destroy.

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <string.h>
 4 #include <pthread.h>
 5 #include <errno.h>
 6  
 7  
 8  
 9 pthread_cond_t cond_child;
10 pthread_cond_t cond_father;
11 
12 pthread_mutex_t mf;
13 
14  
15 void *thread_child(void *arg)
16 {
17     int i,j,k;
18     for(i = 0; i < 50; i++)
19     {
20         for(j = 0; j < 2; j++)
21         {
22             if(pthread_mutex_lock(&mf)!= 0)
23             {
24                 pthread_exit(NULL);
25             }
26             for(k = 0; k < 10; k++)
27                 printf("child is here[%d]\n", k);
28                 pthread_cond_signal(&cond_father);
29                 if(pthread_cond_wait(&cond_child, &mf) != 0)
30                 {
31                     pthread_exit(NULL);       
32                 }
33                 
34                 if(pthread_mutex_unlock(&mf)!= 0)
35                 {
36                     pthread_exit(NULL);
37                 }
38         }
39     } 
40 }
41  
42  
43 int main(int argc, char *argv[])
44 {
45  
46     pthread_t child;
47     int ret;
48     pthread_cond_init(&cond_child, NULL);
49     
50     pthread_cond_init(&cond_father, NULL);
51     //pthread_mutex_init(&mc, NULL);
52     pthread_mutex_init(&mf, NULL);
53      
54      
55     ret = pthread_create(&child, NULL, thread_child, (void*)2);
56     if(ret)
57     {
58         return 1;
59     }
60     
61     int i,j,k;
62     for(i = 0; i < 50; i++)
63     {
64         for(j = 0; j < 2; j++)
65         {
66             if(pthread_mutex_lock(&mf)!= 0)
67             {
68                 pthread_exit(NULL);
69             }
70             
71             if(pthread_cond_wait(&cond_father, &mf) != 0)
72             {
73                 pthread_exit(NULL);       
74             }
75             for(k = 0; k < 100; k++)
76                 printf("father is here[%d]\n", k);
77                 pthread_cond_signal(&cond_child);
78                 
79                 if(pthread_mutex_unlock(&mf)!= 0)
80                 {
81                     pthread_exit(NULL);
82                 }
83                 //printf("other 100 cycle begin[%d]\n", i);
84                 
85         }
86 
87     }
88     pthread_join(child, NULL);
89     pthread_cond_destroy(&cond_father);
90     pthread_cond_destroy(&cond_child);
91     pthread_mutex_destroy(&mf);
92 
93     printf("main thread exit\n");
94     return 0;
95 }

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posted on 2014-08-29 14:34 Notflybird 阅读(291) 评论(0) 收藏举报