Queued listeners in Laravel

Introduction

Queued listeners let your app handle events in the background. This keeps your app fast and smooth for users.

When sending emails after a user registers, so the user doesn't wait.

When processing large files after upload without slowing the app.

When updating external services after a database change.

When running tasks that take time but don't need instant results.

Syntax

Laravel

use Illuminate\Contracts\Queue\ShouldQueue;

class SendWelcomeEmail implements ShouldQueue
{
    public function handle(UserRegistered $event)
    {
        // Send email logic here
    }
}

Implementing ShouldQueue tells Laravel to run this listener in the background.

You need to set up a queue driver (like database or Redis) for queued listeners to work.

Examples

This listener will run in the background when a report is generated.

Laravel

use Illuminate\Contracts\Queue\ShouldQueue;

class ProcessReport implements ShouldQueue
{
    public function handle(ReportGenerated $event)
    {
        // Process report in background
    }
}

This listener runs right away because it does not implement ShouldQueue.

Laravel

class LogUserLogin
{
    public function handle(UserLoggedIn $event)
    {
        // This listener runs immediately (not queued)
    }
}

Queued listener for sending notifications without blocking the app.

Laravel

use Illuminate\Contracts\Queue\ShouldQueue;

class SendNotification implements ShouldQueue
{
    public function handle(NotificationCreated $event)
    {
        // Send notification asynchronously
    }
}

Sample Program

This example shows a queued listener class that handles a UserRegistered event. It logs sending a welcome email. In a real app, Laravel would queue this listener to run in the background.

Laravel

<?php

namespace App\Listeners;

use Illuminate\Contracts\Queue\ShouldQueue;
use App\Events\UserRegistered;
use Illuminate\Support\Facades\Log;

class SendWelcomeEmail implements ShouldQueue
{
    public function handle(UserRegistered $event)
    {
        Log::info('Sending welcome email to: ' . $event->user->email);
        // Imagine sending email here
    }
}

// Event class
namespace App\Events;

class UserRegistered
{
    public $user;

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

// Simulate dispatching event and listener
$user = (object) ['email' => '[e-mail]'];
$event = new UserRegistered($user);
$listener = new \App\Listeners\SendWelcomeEmail();

// Normally Laravel queues this, but here we call directly for demo
$listener->handle($event);

// Output is logged, so we simulate output here
echo "Sending welcome email to: [e-mail]\n";

Important Notes

Queued listeners run asynchronously, so they don't slow down user actions.

Make sure your queue system is configured and running (like database or Redis queues).

Common mistake: forgetting to implement ShouldQueue means the listener runs immediately.

Summary

Queued listeners help run tasks in the background.

Implement ShouldQueue to make a listener queued.

Use queued listeners for slow tasks like sending emails or processing files.