Simple forking for executing tasks

Fork.php

<?php

class CouldNotForkException extends Exception {}

class Fork
{
    private $task;

    public function __construct(Closure $task)
    {
        $this->task = $task;
    }

    public function run()
    {
        // @todo check if pcntl_fork() exists and throw appropriate exception

        $pid = pcntl_fork();

        if ($pid == -1) {
            throw new CouldNotForkException('Received erronious pid.');
        } elseif ($pid) {
            // Parent process
            // Noop
        } else {
            // Child process
            // Execute the task
            $task = $this->task;
            $task();
            exit;
        }
    }

    public function wait()
    {
        pcntl_wait($status);
    }
}

/**
 * This function will generate simple tasks that consist of a random wait time, and an echo call
 *
 * @param mixed $id The id for the task
 */
function getTask($id)
{
    return function() use ($id) {
        $time = rand(1, 10);
        sleep($time);

        echo $id;
    };
}

// Create a list of a few tasks that we want to run simultaniously
$tasks = array();
$tasks[] = getTask(1);
$tasks[] = getTask(2);
$tasks[] = getTask(3);

// Create forks for each task, and run them
$forks = array();
foreach ($tasks as $task) {
    $fork = new Fork($task);
    $fork->run();
    
    $forks[] = $fork;
}

// Wait for running tasks, before proceeding
foreach ($forks as $fork) {
    $fork->wait();
}

echo 'done';