class QCModifiedSubscriber implements EventSubscriberInterface
{
public function __construct(EntityManagerInterface $em, CorrectionReponseService $correctionReponse)
{
    $this->em = $em;
    $this->correctionReponse = $correctionReponse;
}

public static function getSubscribedEvents()
{
    // Liste des évènements écoutés et méthodes à appeler
    return array(
        'qc.modified' => 'calculStats'
    );
}

public function calculStats(Event $event)
{
    $data = $event->getData();
    $QC = $this->em->getRepository(QC::class)->find($data['qcId']);
    $this->correctionReponse->correctionReponsesOfQC($QC);
}

services:
    PACESColleBundleEventListenerQCModifiedSubscriber:
        tags:
            - { name: 'kernel.event_subscriber'}

protected function execute(InputInterface $input, OutputInterface $output)
{
    $em = $this->getContainer()->get('doctrine')->getManager();
    $dispatcher = new EventDispatcher();

    while (true) {
        $processId = rand(0, 999999999);
        # attempts to claim a single event, returns it if successful. may return multiple events.
        // note: $processId is some unique id to this process, helps prevent race conditions (see below)
        $events = $em->getRepository(Event::class)->claimEvent($processId);

        # no events to process, so break out of loop.
        if (count($events) === 0) {
            break;
        }

        # iterate over each event to be processed, typically just 1.
        foreach ($events as $eventEntity) {
            $output->write("Processing id: {$eventEntity->getId()}" . PHP_EOL);

            # create the event...
            $event = new SymfonyComponentEventDispatcherEvent($eventEntity);

            try {
                # dispatch the event!
                $dispatcher->dispatch($eventEntity->getName(), $event);
                # if we made it here we were successful, mark as processed
                $eventEntity->setProcessed(1);

            } catch (Exception $e) {
                $eventEntity->setError((string)$e);
            }

            $em->persist($eventEntity);
            $em->flush();
        }
    }
}