Asynchronous loop

async_loop

function async_loop($array, $function) {
	
	foreach($array as $key => $item) {
		$pid = pcntl_fork();
		if ($pid) {
	        	$childs[] = $pid;
		} else {
			$function($key, $item);
			exit();
		}
	}
	while(count($childs) > 0) {

	    foreach($childs as $key => $pid) {
	        $res = pcntl_waitpid($pid, $status, WNOHANG);
	        
	        // If the process has already exited
	        if($res == -1 || $res > 0)
	            unset($childs[$key]);
	    }   
	}
}

// Use like this:
$subscribers = [
	[
		'id' => 1,
		'name' => 'John Doe'
		'email' => 'johndoe@gmail.com'
	],
	[
		'id' => 2,
		'name' => 'Sarah Joe'
		'email' => 'sarahjoe@gmail.com'
	]
];
async_loop($subscribers, function($key, $subscriber){
	$email = new Send_email($subscriber);
	$email->send();
});