Running multiple processes in PHP

example.php

<?php
set_time_limit(0);
include "threads.php";
$commands = array('ffmpeg -i '.$inputFile[0].' '.$outputFile[0].' 2>&1','ffmpeg -i '.$inputFile[0].' '.$outputFile[0].' 2>&1');
$threads = new Multithread($commands);
$threads->run();
foreach ($threads->commands as $key=>$command){
	echo "Command ".$command.":<br>";
	echo "Output ".$threads->output[$key]."<br>";
	echo "Error ".$threads->error[$key]."<br><br>";
}
?>

multiple-processes.php

<?php
// original: http://www.php-code.net/2010/05/running-multiple-processes-in-php/
// https://web.archive.org/web/20140208211125/http://www.php-code.net/2010/05/running-multiple-processes-in-php
class Thread {
	var $pref ; // process reference
	var $pipes; // stdio
	var $buffer; // output buffer
	var $output;
	var $error;
	var $timeout;
	var $start_time;
 
 
	function Thread() {
		$this->pref = 0;
		$this->buffer = "";
		$this->pipes = (array)NULL;
		$this->output = "";
		$this->error="";
 
		$this->start_time = time();
		$this->timeout = 0;
	}
 
	function Create ($command) {
		$t = new Thread;
		$descriptor = array (0 => array ("pipe", "r"), 1 => array ("pipe", "w"), 2 => array ("pipe", "w"));
		//Open the resource to execute $command
		$t->pref = proc_open($command,$descriptor,$t->pipes);
		//Set STDOUT and STDERR to non-blocking 
		stream_set_blocking ($t->pipes[1], 0);
		stream_set_blocking ($t->pipes[2], 0);
		return $t;
	}
 
	//See if the command is still active
	function isActive () {
		$this->buffer .= $this->listen();
		$f = stream_get_meta_data ($this->pipes[1]);
		return !$f["eof"];
	}
 
	//Close the process
	function close () {
		$r = proc_close ($this->pref);
		$this->pref = NULL;
		return $r;
	}
 
	//Send a message to the command running
	function tell ($thought) {
		fwrite ($this->pipes[0], $thought);
	}
 
	//Get the command output produced so far
	function listen () {
		$buffer = $this->buffer;
		$this->buffer = "";
		while ($r = fgets ($this->pipes[1], 1024)) {
			$buffer .= $r;
			$this->output.=$r;
		}
		return $buffer;
	}
 
	//Get the status of the current runing process
	function getStatus(){
		return proc_get_status($this->pref);
	}
 
	//See if the command is taking too long to run (more than $this->timeout seconds)
	function isBusy(){
		return ($this->start_time>0) && ($this->start_time+$this->timeout<time());
	}
 
	//What command wrote to STDERR
	function getError () {
		$buffer = "";
		while ($r = fgets ($this->pipes[2], 1024)) {
			$buffer .= $r;
		}
		return $buffer;
	}
}
 
 
//Wrapper for Thread class
class Multithread{
	var $output;
	var $error;
	var $thread;
	var $commands = array();
 
	function __construct($commands){
		$this->commands = $commands;
 
		foreach ($this->commands as $key=>$command){
			$this->thread[$key]=Thread::create($command);
		}
	}
 
 
	function run(){
		$commands = $this->commands;
		//Cycle through commands
		while (count($commands)>0){
			foreach ($commands as $key=>$command){
				//Get the output and the errors
				$this->output[$key].=$this->thread[$key]->listen();
				$this->error[$key].=$this->thread[$key]->getError();
				//Check if command is still active
				if ($this->thread[$key]->isActive()){
					$this->output[$key].=$this->thread[$key]->listen();
					//Check if command is busy
					if ($this->thread[$key]->isBusy()){
						$this->thread[$key]->close();
						unset($commands[$key]);
					}
				} else {
					//Close the command and free resources
					$this->thread[$key]->close();
					unset($commands[$key]);
				}
			}
		}
		return $this->output;
	}
}
?>