Backend Worker Patterns

Overview

Backend workers handle asynchronous and long-running tasks outside request-response paths.

Common Patterns

• Queue-based background processing
• Scheduled jobs
• Event-driven consumers
• Retry with dead-letter queues

flowchart LR
    A[API Request] --> B[Queue]
    B --> C[Worker]
    C --> D[(Database)]
    C --> E[Notification Service]

Practical Example

A checkout API enqueues order confirmation work and returns quickly while workers process email and invoice generation asynchronously.

Production Example

Teams implement idempotency keys and visibility timeouts to avoid duplicate processing under retry conditions.

Common Pitfalls

• No retry strategy for transient failures
• Non-idempotent workers causing duplicate side effects
• Missing monitoring on queue lag and failure rates

Key Takeaways

• Worker patterns improve API responsiveness and resilience.
• Idempotency and retry controls are mandatory.
• Queue and worker telemetry should drive operations.