thread同步测试

代码

 1 #include <stdio.h>
 2 #include <pthread.h>
 3 #include <stdlib.h>
 4 #include <semaphore.h>
 5 
 6 #define NUM 5
 7 int queue[NUM];
 8 sem_t blank_number, product_number;
 9 
10 void *producer ( void * arg )
11 {
12     static int p = 0;
13 
14     for ( ;; ) {
15         sem_wait( &blank_number );
16         queue[p] = rand() % 1000;
17         printf("Product %d \n", queue[p]);
18         p = (p+1) % NUM;
19         sleep ( rand() % 5);
20         sem_post( &product_number );
21     }
22 }
23 void *consumer ( void * arg )
24 {
25 
26     static int c = 0;
27     for( ;; ) {
28         sem_wait( &product_number );
29         printf("Consume %d\n", queue[c]);
30         c = (c+1) % NUM;
31         sleep( rand() % 5 );
32         sem_post( &blank_number );
33     }
34 }
35 
36 int main(int argc, char *argv[] )
37 {
38     pthread_t pid, cid;
39     
40     sem_init( &blank_number, 0, NUM );
41     sem_init( &product_number, 0, 0);
42     pthread_create( &pid, NULL, producer, NULL);
43     pthread_create( &cid, NULL, consumer, NULL);
44     pthread_join( pid, NULL );
45     pthread_join( cid, NULL );
46     sem_destroy( &blank_number );
47     sem_destroy( &product_number );
48     return 0;
49 }

运行结果

分析

功能：每一个生产者都要把自己生产的产品放入缓冲池，每个消费者从缓冲池中取走产品消费。在这种情况下，生产者消费者进程同步，因为只有通过互通消息才知道是否能存入产品或者取走产品。他们之间也存在互斥，即生产者消费者必须互斥访问缓冲池，即不能有两个以上的进程同时进行。

2.修改代码

 1 #include <stdio.h>
 2 #include <pthread.h>
 3 #include <stdlib.h>
 4 #include <semaphore.h>
 5 
 6 #define NUM 3
 7 int queue[NUM];
 8 sem_t blank_number, product_number;
 9 
10 void *producer ( void * arg )
11 {
12     static int p = 0;
13 
14     for ( ;; ) {
15         sem_wait( &blank_number );
16         queue[p] = rand() % 6;
17         printf("Product %d \n", queue[p]);
18         p = (p+1) % NUM;
19         sleep ( rand() % 5);
20         sem_post( &product_number );
21     }
22 }
23 void *consumer ( void * arg )
24 {
25 
26     static int c = 0;
27     for( ;; ) {
28         sem_wait( &product_number );
29         printf("Consume %d\n", queue[c]);
30         c = (c+1) % NUM;
31         sleep( rand() % 5 );
32         sem_post( &blank_number );
33     }
34 }
35 
36 int main(int argc, char *argv[] )
37 {
38     pthread_t pid, cid;
39     
40     sem_init( &blank_number, 0, NUM );
41     sem_init( &product_number, 0, 0);
42     pthread_create( &pid, NULL, producer, NULL);
43     pthread_create( &cid, NULL, consumer, NULL);
44     pthread_join( pid, NULL );
45     pthread_join( cid, NULL );
46     sem_destroy( &blank_number );
47     sem_destroy( &product_number );
48     return 0;
49 }

posted on 2021-11-15 11:19 20191208孙汇阳阅读(31) 评论(0) 收藏举报