Linux下的多进程间共享资源的互斥访问

把源代码运行一遍就知道了

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <sys/mman.h> #include <pthread.h> pthread_mutex_t* g_mutex; //创建共享的mutex void init_mutex(void) { int ret; //g_mutex一定要是进程间可以共享的，否则无法达到进程间互斥 g_mutex=(pthread_mutex_t*)mmap(NULL, sizeof(pthread_mutex_t), PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0); if( MAP_FAILED==g_mutex ) { perror("mmap"); exit(1); } //设置attr的属性 pthread_mutexattr_t attr; pthread_mutexattr_init(&attr); //一定要设置为PTHREAD_PROCESS_SHARED //具体可以参考http://blog.chinaunix.net/u/22935/showart_340408.html ret=pthread_mutexattr_setpshared(&attr,PTHREAD_PROCESS_SHARED); if( ret!=0 ) { perror("init_mutex pthread_mutexattr_setpshared"); exit(1); } pthread_mutex_init(g_mutex, &attr); } int main(int argc, char *argv[]) { init_mutex(); int ret; char str1[]="this is child process/r/n"; char str2[]="this is father process/r/n"; int fd=open("tmp", O_RDWR|O_CREAT|O_TRUNC, 0666); if( -1==fd ) { perror("open"); exit(1); } pid_t pid; pid=fork(); if( pid<0 ) { perror("fork"); exit(1); } else if( 0==pid ) { ret=pthread_mutex_lock(g_mutex); if( ret!=0 ) { perror("child pthread_mutex_lock"); } sleep(10);//测试是否能够阻止父进程的写入 write(fd, str1, sizeof(str1)); ret=pthread_mutex_unlock(g_mutex); if( ret!=0 ) { perror("child pthread_mutex_unlock"); } } else { sleep(2);//保证子进程先执行 ret=pthread_mutex_lock(g_mutex); if( ret!=0 ) { perror("father pthread_mutex_lock"); } write(fd, str2, sizeof(str2)); ret=pthread_mutex_unlock(g_mutex); if( ret!=0 ) { perror("father pthread_mutex_unlock"); } } wait(NULL); munmap(g_mutex, sizeof(pthread_mutex_t)); }

运行后tmp文件内容为：

this is child process

this is father process