pthreads stopping already running thread once a condition has been met - php

Question

I'm still relatively new to PHP and trying to use pthreads to solve an issue. I have 20 threads running processes that end at varying times. Most finish around < 10 seconds or so. I don't need all 20, just 10 detected. Once I get to 10, I would like to kill the threads, or to continue on to the next step.
I have tried using set_time_limit to about 20 seconds for each of the threads, but they ignore it and keep running. I am looping through the jobs looking for the join because I didn't want the rest of the program to run but I'm stuck until the slowest one has finished. While pthreads has reduced the time from around a minute to about 30 seconds, I can shave even more time since the first 10 run in about 3 seconds.
Thanks for any help and here is my code:
$count = 0;
foreach ( $array as $i ) {
$imgName = $this->smsId."_$count.jpg";
$name = "LocalCDN/".$imgName;
$stack[] = new AsyncImageModify($i['largePic'], $name);
$count++;
}
// Run the threads
foreach ( $stack as $t ) {
$t->start();
}
// Check if the threads have finished; push the coordinates into an array
foreach ( $stack as $t ) {
if($t->join()){
array_push($this->imgArray, $t->data);
}
}
class class AsyncImageModify extends \Thread{
public $data;
public function __construct($arg, $name, $container) {
$this->arg = $arg;
$this->name = $name;
}
public function run() {
//tried putting the set_time_limit() here, didn't work
if ($this->arg) {
// Get the image
$didWeGetTheImage = Image::getImage($this->arg, $this->name);
if($didWeGetTheImage){
$timestamp1 = microtime(true);
print_r("Starting face detection $this->arg" . "\n");
print_r(" ");
$j = Image::process1($this->name);
if($j){
// lets go ahead and do our image manipulation at this point
$userPic = Image::process2($this->name, $this->name, 200, 200, false, $this->name, $j);
if($userPic){
$this->data = $userPic;
print_r("Back from process2; the image returned is $userPic");
}
}
$endTime = microtime(true);
$td = $endTime-$timestamp1;
print_r("Finished face detection $this->arg in $td seconds" . "\n");
print_r($j);
}
}
}

Answer 1

It is difficult to guess the functionality of Image::* methods, so I can't really answer in any detail.
What I can say, is that there are very few machines I can think of that are suitable to run 20 concurrent threads in any case. A more suitable setup would be the worker/stackable model. A Worker thread is a reuseable context, and can execute task after task, implemented as Stackables; execution in a multi-threaded environment should always use the least amount of threads to get the most work done possible.
Please see pooling example and other examples that are distributed with pthreads, available on github, additionally, much information regarding usage is contained in past bug reports, if you are still struggling after that ...