PHP - Multithread a function with pthreads - php

Question

I'm currently working with pthreads to implement multithreading on a very demanding function. So far I got this working:
class Operation extends Thread {
public function __construct($arg) {
$this->arg = $arg;
}
public function run() {
if ($this->arg) {
$parameters = $this->arg;
echo my_function($parameters[0],$parameters[1]);
}
}
}
$stack = array();
foreach ($work as $operation) { $stack[] = new Operation($operation); };
foreach ($stack as $t) { $t->start(); };
It outputs the results directly.
I'd like to have my results stored one by one in an array (in the same order would be nice) but of course this does not work :
class Operation extends Thread {
public function __construct($arg) {
$this->arg = $arg;
}
public function run() {
if ($this->arg) {
$parameters = $this->arg;
$results[] = my_function($parameters[0],$parameters[1]);
}
}
}
$stack = array();
foreach ($work as $operation) { $stack[] = new Operation($operation); };
foreach ($stack as $t) { $t->start(); };
var_dump($results);
Any help would be appreciated.
Details:
my_function outputs an UTF-8 string.

Answer 1

The basic problem is that arrays are not thread safe, pthreads provides array-like interfaces on all Threaded objects; This means you can use Threaded objects in place of arrays in a multi-threaded context.
<?php
function demanding(...$params) {
/* you have parameters here */
return array(rand(), rand());
}
class Task extends Collectable {
public function __construct(Threaded $result, $params) {
$this->result = $result;
$this->params = $params;
}
public function run() {
$this->result[] =
demanding(...$this->params);
}
protected $result;
protected $params;
}
$pool = new Pool(16);
$result = new Threaded();
while (#$i++<16) {
$pool->submit(
new Task($result, $argv));
}
$pool->shutdown();
var_dump($result);
?>
There isn't a built-in way to do a multi-threaded sort, so the simplest thing to do is sort your result when the threads are finished.

Answer 2

I'm sure someone can do better but it's (apparently) working and it's quite a boost of performance. The "waiting for thread" part is very inefficient and inelegant, any help will be appreciated!
First of all, check if you have pthreads installed with phpinfo() or install it https://php.net/manual/en/pthreads.installation.php .
$key = 0;//We initialise the key to sort our results
foreach($iteration as $parameters) {//We make a loop to create the task list
$arguments[] = array($key,$parameters,$_POST['stuff'],$another_parameter,...);//We index ALL the parameters our function need for each task ($_POST, $_FILES, $_GET, user defined...) in a nice array
++$key;//We increment our key
};
class operation extends Thread {
public $done = 0;//We initialize the "done" indicator
public function __construct($arguments) {
$this->arguments = $arguments;//We put our parameters in a construct
}
public function run() {
if ($this->arguments)
{
$parameters = $this->arguments;//We extract the parameters for this worker
$this->result = array($parameters[0], your_function($parameters[1],$parameters[2],...));//We launch our function and add the key to the result
$this->done = 1;//This thread is done
}
}
}
$stack = array();//Lets initialize our stack
foreach ($arguments as $operation) { $stack[] = new operation($operation); };//We initialize the process
foreach ($stack as $t) { if($t->start()) { $t->join(); }; };//We launch it and wait until all the workers have completed their task
foreach($stack as $strata) {//We get each of the results
while($strate->done == 0) {sleep(1);};//Inefficient way to wait for the thread to complete, ANY HELP WILL BE APPRECIATED
$results[] = $strata->result;//Once it's done we add it to our results array
};
ksort($results);//We sort our array with our key
foreach($results as $line) { $results_sorted[] = $line[1]; };//We delete the key
Now you have your $results_sorted ! Enjoy !