Use symfony/messenger without supervisor

Symfony messenger use Supervisor to keep workers running but not all web hosting have a supervisor.

By default, the command will run forever and handle 10 messages before exiting with memory limit(128M) :

bin/console messenger:consume async --limit=10 --memory-limit=128M

To work around this problem, we will use cronjobs but we don't let workers run forever.
For that we will listen on the event WorkerRunningEvent :

<?php


namespace App\Event;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Messenger\Event\WorkerRunningEvent;

/**
 * Class ExtractFailedEvent
 * @package App\Event
 */
class CronRunningEvent implements EventSubscriberInterface
{
    public function onWorkerRunning(WorkerRunningEvent $event): void
    {
        if ($event->isWorkerIdle()) {
            $event->getWorker()->stop();
        }
    }

    /**
     * @return array<string>
     */
    public static function getSubscribedEvents()
    {
        return [
            WorkerRunningEvent::class => 'onWorkerRunning',
        ];
    }
}

Method isWorkerIdle() return true when no message has been received by the worker.
If no message has been received , we stop the worker

To finish, set up a cron job to run evry minute

* * * * * bin/console messenger:consume async --memory-limit=128M

Simple and easy!

Comments

[Damien Alexandre]

I fear you are going to saturate your server with consumers if your message queue gets filled with messages. As it's never empty, the worker never stops, and you create a new one every minute - without any limit / safeguard.

You could leverage the Lock component to make sure there are never two consumers running at the same time.

[Dennis]

Actually it won't keep going seeing as he used --limit=10. So it'd stop at 10 anyway and can't continually keep going if the message queue gets full of messages. So I suppose it's more of a "Good morning. Wake up. Check phone for messages. Only go through 10 messages. Stop. Go back to bed till the next minute."

[sebastianrozmus]

I agree with Damien. To avoid that I would recommend to add --time-limit=60

[Nacho Colomina Torregrosa]

Yes, i agree, it would resolve the problem of having so many workers if there are always messages

[Paul Rijke]

Brilliant trick... I actually postponed using Messenger because of the worker problem on my shared hosting.

[F.R Michel]

I had the same problem.

[Chrishow2]

Excellent and elegant...I solved mi problem in half a minute. Thanks a lot man!

[Dennis]

In the docs it says:

To properly stop a worker, throw an instance of StopWorkerException.