Timeouts, retries, backoff, and idempotency
By the end of today you can make a call to something unreliable without making the outage worse, and explain why a naive retry is one of the most dangerous three lines of code you can write.
YesterdayOn Day 24 you learned idempotency as a property of HTTP methods. Today it becomes the thing that makes retrying survivable.
TomorrowTomorrow you consolidate the phase into a readiness checklist you could hand to a colleague.
Why this matters
Retries without backoff and jitter have caused some of the largest outages in the industry. The failure mode is that your recovery attempt becomes the attack.
- Timeouts
- Retries with backoff and jitter
- Idempotency keys
- Circuit breakers
- Rate limiting
Learn it
80 minCopy this into Claude or ChatGPT. It quizzes you before it explains anything, which is deliberate. The resources under it are how you check what it told you.
Today's Master Prompt
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Check it against something that is not a model
An assistant can be fluent and wrong, and on a topic you met today you will not catch it. These cover the same ground and were made by people who do this for a living, so they are what you hold the explanation up against. They are other people's work and we only link to them, so judge them for yourself.
3 hand-picked resources
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Build it
50 minWrite a client for an unreliable endpoint with a sensible timeout, exponential backoff with jitter, and a maximum attempt count. Simulate a service failing 50 percent of the time and confirm your client succeeds without hammering it. Then add an idempotency key to a write operation and prove a repeated call does not act twice.
Recall it
20 minAnswer out loud, reveal, then mark honestly whether you had it. That score is the only thing on this page you do not get to choose.
5 recall questions
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Rate it
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Mastery tracking
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Recap
- 01A call with no timeout can hold resources forever and exhaust your capacity
- 02A timeout does not tell you whether the operation happened
- 03Backoff without jitter produces synchronised retry waves
- 04An idempotency key is what makes retrying a write survivable
Your progress
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