淘宝上做淘宝客的网站,WordPress代码实现标签页面,做分析仪器推广的网站,wordpress跳转链接介绍通常后台服务器程序都必须有且只有一个进程#xff0c;那么如何单进程呢#xff1f;本例子是通过flock函数对/var/run/myserver.pid记录pid文件的进行加锁若加锁不正常#xff0c;说明后台服务进程已经在运行了#xff0c;这时则直接报错退出若加锁成功#xff0c;说明…介绍通常后台服务器程序都必须有且只有一个进程那么如何单进程呢本例子是通过flock函数对/var/run/myserver.pid记录pid文件的进行加锁若加锁不正常说明后台服务进程已经在运行了这时则直接报错退出若加锁成功说明后台服务进程没有在运行这时可以正常启用进程后台服务程序单进程控制详细不多说直接看代码#include #include #include #include #include #include #define PID_BUF_LEN (20)#define RUN_PID_FILE /var/run/myserver.pid//服务进程单实例运行//返回值: 1--正在运行0--未运行-1--出错int server_is_running(){int fd open(RUN_PID_FILE, O_WRONLY|O_CREAT);if(fd 0){printf(open run pid err(%d)! %s, errno, RUN_PID_FILE);return -1;}// 加锁// LOCK_SH 建立共享锁定。多个进程可同时对同一个文件作共享锁定。// LOCK_EX 建立互斥锁定。一个文件同时只有一个互斥锁定。if(flock(fd, LOCK_EX|LOCK_NB) -1){//加不上锁则是服务正在运行已上锁了printf(server is runing now! errno%d, errno);close(fd);return 1;}// 加锁成功证明服务没有运行// 文件句柄不要关也不要解锁// 进程退出自动就解锁了printf(myserver is not running! begin to run..... pid%ld, (long)getpid());char pid_buf[PID_BUF_LEN] {0};snprintf(pid_buf, sizeof(pid_buf)-1, %ld, (long)getpid());// 把进程pid写入到/var/run/myserver.pid文件write(fd, pid_buf, strlen(pid_buf));return 0;}int main(void){//进程单实例运行检测if(0 ! server_is_running()){printf(myserver process is running!!!!! Current process will exit !);return -1;}while(1){printf(myserver doing ...);sleep(2);}return 0;}运行结果运行程序可知进程pid是6965[rootlincoding singleprocess]# ./myserverserver is not running! begin to run..... pid6965myserver doing ...myserver doing ...myserver doing ...myserver doing ...myserver doing ...myserver doing ...myserver doing ...myserver doing .../var/run/myserver.pid也记录此进程的pid号ps auxf | grep myserver可知mysever进程一直运行着[rootlincoding singleprocess]# cat /var/run/myserver.pid6965[rootlincoding singleprocess]#[rootlincoding singleprocess]# ps auxf | grep myserverroot 6965 0.0 0.0 3924 460 pts/0 S 00:32 0:00 | \_ ./myserverroot 9976 0.0 0.0 103256 856 pts/1 S 00:35 0:00 \_ grep myserver[rootlincoding singleprocess]#此时再运行myserver程序这时会报错退出因为检测到myserver程序已经在运行中不可以起另外一个进程从而达到了后台服务程序单进程控制[rootlincoding singleprocess]# ./myserverserver is runing now! errno11myserver process is running!!!!! Current process will exit !
