Idempotency, Exactly‑Once, and Other Lies We Tell Ourselves
Distributed systems don’t behave the way the docs say they do. We’re told we have “exactly‑once delivery,” “guaranteed processing,” and “idempotent handlers,” but the moment a region fails over, a consumer crashes mid‑write, or an operator hits “retry,” those guarantees evaporate. This session cuts through the marketing and shows what really happens inside queues, event buses, and serverless runtimes when the world gets messy.
Learning Objectives
- Explain why “exactly‑once” and similar delivery guarantees break down in real distributed systems, including how retries, partial failures, and operator intervention inevitably produce duplicates and replays.
- Design idempotent workflows that remain correct under duplicate and out‑of‑order execution, using patterns that protect state transitions and prevent data corruption when failures occur mid‑process.
- Recover safely from failure scenarios that have already gone wrong, applying architectural patterns that make systems durable, debuggable, and resilient even after guarantees have been violated.