互斥锁-多线程

 1 #include <stdio.h>
 2 #include <unistd.h>
 3 #include<signal.h> 
 4 #include <stdlib.h>
 5 #include <pthread.h>
 6 #include "../headx.h"
 7 
 8 
 9 pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;     // 静态的初始化锁
10  
11 void test_xxx(void)
12 { 
13     int num = 0; 
14     do { 
15         pthread_mutex_lock(&mutex);
16         dbg("线程 %d", num++);   
17         pthread_mutex_unlock(&mutex);   
18         usleep(1); 
19     } while(1);      
20 }
21 
22 int main(void) 
23 {
24     dbg("互斥锁-线程");
25     
26     pthread_t thread;        
27     if(pthread_create(&thread, NULL, V(test_xxx), NULL)) dbge();      
28     do {                    
29         pthread_mutex_lock(&mutex);
30         sleep(2);  
31         pthread_mutex_unlock(&mutex);  
32         
33         /*
34          * 必须加一个延时
35          * 因为刚释放，刚好CPU时间还没用完，
36          * 又立马加锁了，导致资源一直被当前进程占用 
37          */
38         usleep(1);              
39     } while(1); 
40 }
41 
42 // gcc 2.互斥锁.c -pthread 

 

互斥锁-多进程

 1 #include <stdio.h>
 2 #include <unistd.h>
 3 #include<signal.h> 
 4 #include <stdlib.h>
 5 #include <pthread.h>
 6 #include "../headx.h"
 7 
 8 
 9 void *anonymous_mmap_init(void)
10 {
11     void *addr = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
12     if(V(-1) == addr) dbge();  
13     return addr; 
14 }
15  
16 static void inline *process_mutex_init(void)
17 {
18     pthread_mutexattr_t mutex_attr;            // 互斥锁属性
19     pthread_mutexattr_init(&mutex_attr);    // 初始化互斥锁属性 
20     
21     // 设置互斥对象为PTHREAD_PROCESS_SHARED共享，即可以在多个进程的线程访问,PTHREAD_PROCESS_PRIVATE为同一进程的线程共享
22     pthread_mutexattr_setpshared(&mutex_attr, PTHREAD_PROCESS_SHARED);
23     
24     // 设置同步健壮属性 (https://blog.csdn.net/qq_31442743/article/details/105025450)
25     pthread_mutexattr_setrobust(&mutex_attr, PTHREAD_MUTEX_ROBUST);
26  
27     pthread_mutex_t* shm_mutex = anonymous_mmap_init();
28     pthread_mutex_init(shm_mutex, &mutex_attr);                // 动态的初始化锁 
29     
30     return shm_mutex;
31 }
32 
33 int main(void)  
34 {
35     dbg("互斥锁-进程"); 
36      pthread_mutex_t* shm_mutex = process_mutex_init();
37 
38     int pid;
39     if(-1 == (pid = fork())) dbge();
40     if(!pid) {   
41         uint num = 0;
42         do { 
43             pthread_mutex_lock(shm_mutex);
44             dbg("子进程 %d", num++);
45             pthread_mutex_unlock(shm_mutex);   
46             usleep(1);  
47         } while(1);           
48     }   
49     do {                      
50         pthread_mutex_lock(shm_mutex); 
51         sleep(2);  
52         pthread_mutex_unlock(shm_mutex);   
53         usleep(1); 
54     } while(1); 
55 } 
56  
57 
58 // gcc 2.互斥锁.c -pthread 

// https://blog.csdn.net/quantum7/article/details/85049258