Code example for PHP process management

This article brings you code examples about PHP process management. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

This article is a supplement and improvement to the previous article. Create a master process, install a timer in the master process, detect the queue length every 5 minutes, and calculate it based on the queue length. The required worker process,

then create or kill the child process. The advantage of this is to prevent the queue from piling up and tasks not being processed in time. To update the business code, only the reload operation is required.

The entire process has the following knowledge points:

• Steps to create a daemon process:

1. Settings Default file permissions

2. Fork a process, the parent process exits

3. Call setsid to create a new session

4. Change the current working directory to the root directory

5. Close file descriptors no longer needed

• Use Signal implementation timer

The previous article's timer depends on the system's scheduled tasks. This time it is implemented using the alarm clock signal. Versions below PHP 5.3.0 rely on ticks, 5.3.0 and The above versions can use pcntl_signal_dispatch

Signal: Provides a method of asynchronous event processing. When a signal occurs, the process has the following three ways to process the signal

1. Ignore this signal

2. Capture the signal

3. Perform the system default action. The default action for most signals is to terminate the process

• ##Common signals

SIGKILL and SIGSTOP are two signals that cannot be ignored and captured by users

SIGINT( 2): Program termination signal, usually issued when Ctrl-C), used to notify the foreground process group to terminate the process

SIGQUIT(3): Similar to SIGINT, but is sent by the QUIT character (usually Ctrl /) Control. When the process receives this message and exits, a core file will be generated

SIGKILL(9): Terminate the process immediately and cannot be ignored or blocked

SIGUSR1(10): User-defined signal

SIGUSR2(12): Leave it to the user

SIGALRM(14): Alarm clock signal

SIGTERM(15): Terminate the process and can be captured by the program so that the process can be completed Cleanup operations.

SIGSTOP(19): Stop a process. The process has not ended yet. It just suspends execution.

• Prevents the generation of zombie processes

All processes will become zombie processes when they exit. At this time, if the parent process is still running and wait or waitpid is not called, the resources occupied by the zombie process will not be cleaned up. If the parent process has terminated, the zombie process will be started by init. process to clean up.

Deploy the business code, the main code is as follows

One thing to note is that when creating a daemon process to close the input and output, and the error output stream, if there is echo, etc. behind the code Output characters, a fatal error will occur, and the output stream needs to be redirected to /dev/null in the php code. Or redirect when the terminal starts the process

<?php
define(&#39;PROC_MAX&#39;, 10);
define(&#39;PROC_MIN&#39;, 5);

$cmd = $argv[1];
$aPid = [];
$pidFile = __DIR__ . &#39;/pid.pid&#39;;
$pid = file_get_contents($pidFile);

switch($cmd){
    case &#39;start&#39; :
        if(posix_kill($pid, 0)){
            echo "gamelog process is already exsits!\n";
            return false;
        }
        //设置默认文件权限
        umask(022);
        //fork
        $pid = pcntl_fork();
        if($pid < 0){
            exit(&#39;fork error!&#39;);
        }else if($pid > 0){
            exit;
        }
        //脱离当前终端
        posix_setsid();
        //将当前工作目录更改为根目录
        chdir(&#39;/&#39;);
        //关闭文件描述符
        fclose(STDIN);
        fclose(STDOUT);
        fclose(STDERR);
        //重定向输入输出
        global $STDOUT, $STDERR;
        $STDOUT = fopen(&#39;/dev/null&#39;, &#39;a&#39;);
        $STDERR = fopen(&#39;/dev/null&#39;, &#39;a&#39;);
        
        cli_set_process_title(&#39;gamelog:master&#39;);
        $pid = posix_getpid();
        file_put_contents($pidFile, $pid);
        //闹钟信号
        pcntl_signal(SIGALRM, function() use (&$aPid) {
            pcntl_alarm(300);
            $workerNum = mt_rand(1, 20);//此处检测你需要的进程数
            $daemonNum = count($aPid);
            
            ($workerNum > PROC_MAX) && ($workerNum = PROC_MAX);
            if($daemonNum < $workerNum){
                $procNum = $workerNum - $daemonNum;
                $procNum = max(PROC_MIN, $procNum);
                for($p = 1; $p <= $procNum; $p++){
                    $pid = pcntl_fork();
                    if ($pid < 0) {
                        exit(&#39;fork error!&#39;);
                    } else if ($pid == 0) {
                        cli_set_process_title(&#39;gamelog:worker&#39;);
                        while (true) {
                            //do your work
                            usleep(100);
                        }
                        exit();
                    } else {
                        $aPid[] = $pid;
                    }
                }
            }else if($daemonNum > $workerNum){
                $wokerNum = max($wokerNum, PROC_MIN);
                $killNum = $daemonNum - $workerNum;
                foreach($aPid as $key=>$pid){
                    if(posix_kill($pid, SIGKILL)){
                        unset($aPid[$key]);
                        if(--$killNum <= 0){
                            break;
                        }
                    }
                }
            }
        }, false);
        
        pcntl_signal(SIGUSR1, function() use (&$aPid, $pid){
            foreach($aPid as $key=>$chpid){
                if(!posix_kill($chpid, SIGKILL)){
                    echo "kill child $chpid faild\n";
                }
            }
            posix_kill($pid, SIGKILL);
        }, false);
        
        pcntl_signal(SIGUSR2, function() use (&$aPid, $pid){
           foreach($aPid as $key=>$chpid){
                if(!posix_kill($chpid, SIGKILL)){
                    echo "kill child $chpid faild\n";
                }
            }
            if(!posix_kill($pid, SIGALRM)){
                echo "restart gamelog faild\n";
            }
        }, false);
        
        posix_kill($pid, SIGALRM);
        while (true) {
            pcntl_signal_dispatch();
            $pid = pcntl_wait($status, WUNTRACED);//不阻塞
        }
        break;
    
    case &#39;stop&#39; :
        if(!posix_kill($pid, SIGUSR1)){
            exit(&#39;stop gamelog process error!&#39;);
        }
        break;
    case &#39;reload&#39; :
        if(!posix_kill($pid, SIGUSR2)){
            exit(&#39;restop gamelog process error!&#39;);
        }
        break;
    default :
        echo "Useage php signal.php start|stop|reload\n";
}

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