Swoole_proces Implementing multiple Processes

Brief introduction

Swoole_process is a process management module provided by Swoole to replace the pcntl extension of PHP.

First, make sure that the Swoole version of the installation is greater than 1.7.2:

php --ri swooleswooleswoole support => enabledVersion => 1.10.1

Example description

In this case, three shell commands are consumed, and a sub-process is created to consume them. Spend 1 seconds of sleep deliberately to see the effect visually.

process_t1.php

<?php$start _time=Microtime(TRUE);$cmds=[    "Uname",    "Date",    "WhoAmI"];foreach ($cmds  as $cmd){$process=NewSwoole_process( "My_process", true);    $process->start();    $process->write($cmd); //Send data to child process via pipeline    Echo $rec=$process->read();//Synchronous blocking read pipeline data}//Sub-processfunctionMy_process(Swoole_process$worker){Sleep(1);//intentionally suspended 1s    $cmd=$worker->read();    //$return = EXEC ($cmd);//exec outputs only the last line of the command execution result, and requires an explicit print output    Ob_start();    PassThru($cmd);//Execute external program and display unprocessed, raw output, print output directly.     $return=Ob_get_clean();    if(!$return) $return=' null ';        $worker->write($return);//Read and return data by pipe, or use echo instead of write    //Echo exec ($return);//Read and return data by pipe}//Child process end must be performed wait to recycle or the child process will become a zombie process while($ret= Swoole_process::wait()){//$ret is the number group code is the process exit status code,    $pid=$ret[' pid '];    Echo Php_eol."Worker Exit, pid=".$pid.Php_eol;}$end _time=Microtime(TRUE);Echo sprintf("Use time:%.3f s\ n", $end _time-$start _time);

Run on the command line:

php process_t1.php  LinuxSat Apr 21 15:29:55 CST 2018rootWorker Exit, PID=672Worker Exit, PID=674Worker Exit, PID=676use time:3.080 s

Everyone will feel very strange, why open three sub-process, or use 3 seconds, it should be about 1 seconds or so.

The reason is that when the parent process reads the data returned by the child process, it is synchronous blocking reads:

echo$rec$process->read();//同步阻塞读取管道数据

The result is that the parent process waits for each process to finish processing and returns content before going to the next loop.

Solution 1:
Use the swoole_event_add join pipeline to the event loop to become asynchronous mode:

// echo $rec = $process->read();//同步阻塞读取管道数据//使用swoole_event_add将管道加入到事件循环中，变为异步模式swoole_event_add($process->pipe,function($pipe)use($process) {    echo$rec$process->read();        swoole_event_del($process->pipe);//socket处理完成后，从epoll事件中移除管道});

Execution Result:

Worker Exit, PID=686Worker Exit, PID=687Worker Exit, PID=688use time:1.060 sLinuxSat Apr 21 15:37:14 CST 2018root

You will find that the use time data is not printed last. It's already asynchronous. The actual execution time is around 1s.

Solution 2:
The return value of the child process is not fetched first, and returns uniformly after the loop is completed:

foreach ($cmds  as $cmd){$process=NewSwoole_process( "My_process", true);    $process->start();    $process->write($cmd); //Send data to child process via pipeline    $process _arr[]=$process;}foreach ($process _arr  as $process){Echo $rec=$process->read();}

Execution Result:

LinuxSat Apr 21 15:52:24 CST 2018rootWorker Exit, PID=694Worker Exit, PID=693Worker Exit, PID=695use time:1.061 s

Reference

1. Process
Https://wiki.swoole.com/wiki/page/p-process.html
2, Swoole_process->read
Https://wiki.swoole.com/wiki/page/217.html

Swoole_proces Implementing multiple Processes