Implementation method of PHP background daemon in Linux environment

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Application scenarios

In some cases, we need to continuously and periodically provide some services, such as monitoring the operating status of memory or CPU. These applications have nothing to do with the client. It does not mean that if the client (such as web interface, mobile app, etc.) is closed, we will not monitor the memory or CPU. In order to deal with this business scenario, the background daemon can come in handy.

Required environment

Linux

Implementation method

1. Prepare the php script

in /usr/local In the /src/ directory, create a new daemon.php script file as follows:

##[php] view plain copy

<?php  
  
Class Daemon{  
      
    /** 
     * 初始化一个守护进程 
     * @throws Exception 
     */  
    public function init(){  
        //创建一个子进程  
        $pid = pcntl_fork();  
          
        if ($pid == -1) {  
            throw new Exception(&#39;fork子进程失败&#39;);  
        } elseif ($pid > 0) {  
            //父进程退出,子进程变成孤儿进程被1号进程收养，进程脱离终端  
            exit(0);  
        }  
          
        //创建一个新的会话，脱离终端控制，更改子进程为组长进程  
        $sid = posix_setsid();  
        if ($sid == -1) {  
            throw new Exception(&#39;setsid fail&#39;);  
        }  
          
        //修改当前进程的工作目录，由于子进程会继承父进程的工作目录，修改工作目录以释放对父进程工作目录的占用。  
        chdir(&#39;/&#39;);  
          
        /** 
         * 通过上一步，我们创建了一个新的会话组长，进程组长，且脱离了终端，但是会话组长可以申请重新打开一个终端，为了避免 
         * 这种情况，我们再次创建一个子进程，并退出当前进程，这样运行的进程就不再是会话组长。 
         */  
        $pid = pcntl_fork();  
        if ($pid == -1) {  
            throw new Exception(&#39;fork子进程失败&#39;);  
        } elseif ($pid > 0) {  
            //再一次退出父进程，子进程成为最终的守护进程  
            exit(0);  
        }  
        //由于守护进程用不到标准输入输出，关闭标准输入，输出，错误输出描述符  
        fclose(STDIN);  
        fclose(STDOUT);  
        fclose(STDERR);  
    }  
}  
  
$daemon = new Daemon();  
$daemon->init();  
  
//处理业务代码  
while(true) {  
    file_put_contents(&#39;/usr/local/src/log.txt&#39;, time().PHP_EOL, FILE_APPEND);  
    sleep(5);  
}

2. Run the php script in background mode

At the command line, enter:

[plain]

nohup php /usr/local/src/daemon.php &

At the command line, enter ：

[plain]

tail -f /usr/local/src/log.txt

4. 关闭php后台进程

首先，我们需要查出该进程的PID，命令：

[plain] view plain copy

1. ps -ef | grep "php /usr/local/src/daemon.php"

   Copy after login

然后，通过这个PID把该进程kill掉

[plain] view plain copy

1. kill -9 22767

   Copy after login

   其中，22767就是php后台进程的PID号。

   5. 开机自启

   通过前面的步骤，我们知道如何开启和关闭一个php进程，但是，在实际的应用中，我们不可能每次都是手动开启，这样我们就会损失掉一部分业务数据，所以我们必须要让该进程开机自动运行，步骤如下：

   在/etc/rc.local文件中，将nohup php /usr/local/src/daemon.php &这个命令加入即可。

   相关推荐：

   php后台守护进程+进程信号处理

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