Dead Letter Queue

Definitions

1. A special queue where messages that can't be processed (after exceeding retry limits) are stored for later analysis instead of being discarded. Prevents poison messages from blocking the main queue and enables debugging of failure patterns. Used in SQS, RabbitMQ, and Kafka.

   In plain English: A holding area for failed messages that couldn't be processed, so you can look at them later and figure out what went wrong.

   Example: "Check the dead letter queue — there are 200 failed payment webhook events that need to be investigated and replayed."

Related Terms

• Idempotent
• Webhook vs. Polling
• Event-Driven Architecture
• Circuit Breaker
• Idempotency Key
• Idempotent Pipeline
• Pub/Sub
• Outbox Pattern
• Kafka Topic
• Redis Pub/Sub