<?php
class hashThread extends Thread {

    private $max = 1;
    private $index = 0;

    function __construct($max, $index)
    {
        $this->max = $max;
        $this->index = $index;
    }

    public function run()
    {
        if (in_array($this->index, [2,4,6,8])) {
            require 'null';
        }

        if (in_array($this->index, [7])) {
            throw Exception("stop");
        }

        for ($i=1; $i<=$this->max; $i++)
        {
            md5($i);
        }

        echo "Thread #{$this->index} finished\r\n";
    }
}

$threads = array();
$thread_count = 8;
$start_time = microtime(true);

while($thread_count--)
{
    $threads[$thread_count] = new hashThread(rand(10000, 100000), $thread_count);
    $threads[$thread_count]->start(PTHREADS_INHERIT_NONE);
}

array_map(function($thread) { $thread->join(); }, $threads);

echo "Done in: " . round(microtime(true) - $start_time, 2) . " seconds\r\n";