Dead-letter queues and delayed retry
On This Lesson 4 topics
This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.
In this lesson
isolate poison messages and retry with a delay.
Planned topics
- A dead-letter exchange (DLX) receives messages that are rejected without requeue, expire (TTL), or overflow a queue.
- Set
x-dead-letter-exchange(and optionallyx-dead-letter-routing-key) as queue arguments. - Delayed retry pattern: failed message goes to a wait queue with a TTL whose dead-letter target is the main exchange; it returns after the delay.
- Count retries (header
x-deathor your own) and park the message in a final DLQ after N attempts. - A delayed-message plugin exists; verify availability and support status before recording.
- Alert on DLQ depth and make replay a deliberate action.
Draft outline details
Demonstration
main queue → reject → retry queue (TTL 10 s) → back to main; after 3 tries → DLQ.
Check your understanding
What stops an infinite redelivery loop?
Show answer
A retry limit and a dead-letter queue.
Practice
Apply this lesson with the module's lab, exercises and quiz.
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