.NET Architecture & System Design Interview Question #46

What is a poison message?

Caching, CDN, Queues & Asynchronous Processing Junior Beginner

Quick Interview Answer

A poison message is a message that repeatedly fails processing because of invalid content, an incompatible schema, an unrecoverable business condition, or a persistent application defect.

Detailed Explanation

A poison message is a message that repeatedly fails processing because of invalid content, an incompatible schema, an unrecoverable business condition, or a persistent application defect.

Blind retries waste resources and can block progress. Systems normally limit retries and then move the message to a dead-letter location for investigation or controlled reprocessing.

Code Example

Message
  -> retry 1 fails
  -> retry 2 fails
  -> retry 3 fails
  -> DLQ