Multi-process application in PHP CLI mode_PHP tutorial

PHP is not suitable for being a resident SHELL process in many cases. It does not have a dedicated gc routine and no effective memory management method. Therefore, if you use PHP as a resident SHELL, you will often be consumed by memory. It will lead to abort and unhappy.

Moreover, if the input data is illegal and the script does not detect it, resulting in an abort, it will also make you very unhappy.

So? What to do?

Haha, don’t worry, multi-process will help you!

Then, why is this?

Advantages:

1. Use multiple processes. After the child process ends, the kernel will be responsible for recycling resources

2. When using multiple processes, the abnormal exit of the child process will not cause the entire process Thread to exit. The parent process will also have the opportunity to rebuild the process.

3. A resident main process, only responsible for task distribution, the logic is clearer.

Then, how to do it?

Next, we use the POSIX and Pcntl series functions provided by PHP to implement a PHP command parser. The main process is responsible for accepting user input, and then forks the child process to execute, and is responsible for echoing the end status of the child process.

The code is as follows. I have added comments. If there is anything you don’t understand, you can read the relevant functions in the manual or reply to the message.

　#!/bin/env php

　/**A example denoted muti-process application in php

　　* @filename fork.php

　　* @touch date Wed 10 Jun 2009 10:25:51 PM CST

　　* @author Laruence

　　* @license http://www.zend.com/license/3_0.txt　　 PHP License 3.0

　　* @version 1.0.0

　　*/

　/**Make sure this function can only be run in SHELL*/

if

　(substr(php_sapi_name(), 0, 3) !== 'cli')

　{

　die("This Programe can only be run in CLI mode");

　}

　/**Turn off the maximum execution event limit. In CLI mode, this statement is actually unnecessary.*/

set_time_limit(0);

　$pid　 = posix_getpid(); //Get the main process ID

　$user = posix_getlogin(); //Get user name

echo

　<<

USAGE: [command | expression]

　input php code to execute by fork a new process

input quit to exit

Shell Executor version 1.0.0 by laruence

EOD;

while

　(true)

　{

　$prompt = "n{$user}$ ";

　$input　 = readline($prompt);

readline_add_history($input);

if

　($input == 'quit')

　{

break;

　}

Process_execute($input . ';');

　}

exit(0);

Function

Process_execute($input)

　{

　$pid = pcntl_fork(); //Create child process

if

　($pid == 0)

　{//Subprocess

$pid = posix_getpid();

echo

　"* Process {$pid} was created, and Executed:nn";

eval($input); //Parse command

exit;

　}

else

　{//Main process

　$pid = pcntl_wait($status, WUNTRACED); //Get the child process end status

if

　(pcntl_wifexited($status))

　{

echo

　"nn* Sub process: {$return['pid']} exited with {$status}";

　}

　}

　}

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