PHP Queue Workers

Also Known As

TL;DR

Explanation

PHP queue workers process jobs from queues (Redis, SQS, database) in persistent background processes. Laravel Horizon: dashboard with real-time metrics, auto-scaling worker pools, per-queue configuration, memory limit enforcement. Supervisor: process control system that monitors and restarts crashed workers, manages multiple worker processes with log rotation. Job patterns: $tries and $backoff for retry logic, failed() hook for cleanup on permanent failure, ShouldBeUnique for deduplication.

Common Misconception

Why It Matters

Common Mistakes

• Workers started manually without Supervisor — crashed workers never restart
• No memory limit — PHP workers accumulate memory leaks over time without restart
• No job timeout — a hanging job blocks that worker indefinitely
• Single worker handling all job types — slow report generation blocks fast email sending

Code Examples

# Manual worker without process management:
php artisan queue:work &
# Worker crashes: nobody notices
# Queue backs up silently
# Server restarts: worker never comes back
# 2 hours later: customer reports emails not sending

# /etc/supervisor/conf.d/horizon.conf:
[program:horizon]
process_name=%(program_name)s
command=php /var/www/app/artisan horizon
autostart=true
autorestart=true
user=www-data
stopwaitsecs=3600
stdout_logfile=/var/log/supervisor/horizon.log

# config/horizon.php — separate queues, memory limits:
# 'supervisor-1' => ['queue'=>['critical','default','low'],'processes'=>10,'memory'=>128]

References

• ↗ https://laravel.com/docs/horizon

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