pthread_mutex互斥锁多进程共享

#include <pthread.h>#include <stdio.h>#include <stdlib.h>#include <sys/mman.h>#include <unistd.h>#include <sys/types.h>#include <sys/wait.h>typedef struct _FOO{int nCount;int nData;}FOO,*PFOO;int main(int argc,char *argv[]){FOO *ptr;pid_t pid;pthread_mutexattr_t mutexattr;pthread_mutex_t mutex;pthread_mutexattr_init(&mutexattr);pthread_mutexattr_setpshared(&mutexattr,PTHREAD_PROCESS_SHARED);//设置为进程共享pthread_mutex_init(&mutex,&mutexattr);ptr = (PFOO)mmap(NULL,sizeof(FOO),PROT_READ | PROT_WRITE,MAP_SHARED|MAP_ANON,-1,0);//匿名内存映射，让父子进程都操作ptr指向的内存区，如果不使用共享内存，则父子进程的ptr指向的是各自的内存空间ptr->nCount = 1;ptr->nData = 2;printf("%d,%d\n",ptr->nCount,ptr->nData);if( (pid = fork()) < 0){printf("fork error\n");return -1;} else if( 0 == pid)//子进程{for(int i = 0;i<3;i++){pthread_mutex_lock(&mutex);ptr->nCount++;printf("child ++ === %d\n",ptr->nCount);pthread_mutex_unlock(&mutex);usleep(1000);}}else//父进程{for(int i = 0;i<3;i++){pthread_mutex_lock(&mutex);ptr->nCount += 2;printf("parent +2 === %d\n",ptr->nCount);pthread_mutex_unlock(&mutex);usleep(1000);}}waitpid(pid,NULL,0);munmap(NULL,sizeof(FOO));return 0;}