Lab 04 — Force a redelivery

Goal

Kill a consumer mid-processing and watch ApproximateReceiveCount climb.

Setup

To be written — CLI commands and an IaC equivalent for every resource, all prefixed sqs-course-.

Steps

1. Write a consumer that receives, sleeps 60 s, then deletes
2. Set visibility timeout to 30 s
3. Run it; while it sleeps, start a second consumer
4. Observe both consumers holding the same message
5. Kill the first consumer before it deletes
6. Receive again and read ApproximateReceiveCount

What you should observe

• Two consumers processing the same message simultaneously — the race from Module 08
• ApproximateReceiveCount increments on every receive, not on every failure
• This is the exact scenario idempotency exists for

Why it happened

To be written — ties each observation back to the mechanism in 05 — The Message Lifecycle.

Experiments to try

To be written — deliberate variations that change the outcome.

Teardown

To be written — every resource created above, in dependency order.

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