queue-management Skill

Goal

Async messaging is powerful but dangerous. Messages must never be lost.

Steps

1. Dead Letter Queues (DLQ)

• Rule: Every consumer MUST have a configured DLQ.
• Behavior: If a message fails processing N times (Poison Pill), move it to DLQ. Alert ops-sre.
• Replay: Must have a mechanism to replay messages from DLQ after bug fix.

2. Idempotency

• Rule: All consumers handle(msg) must be idempotent.
• Pattern:
  1. Check processed_messages table for msg.id.
  2. If found, ack and ignore.
  3. If not, process transactionally.
  4. Save msg.id to processed_messages.