Multi Step Processes easy
A message in your job queue is malformed and causes the worker code to crash every time it tries to process it. After 5 failed attempts, what should the system do with the message?
- A Delete it silently.
- B Move it to a Dead Letter Queue (DLQ) for manual inspection.
- C Keep retrying it forever.
- D Stop the entire queue processing system.
Answer: B. Move it to a Dead Letter Queue (DLQ) for manual inspection.
Retrying forever (C) blocks other work (Poison Pill). Deleting silently (A) causes data loss. A DLQ isolates the bad message so engineers can debug it later without stopping the system.
One system design question a day, with spaced repetition so the ones you miss come back.
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