https://blog.yusukeikoma.com/tags/idempotency/Recent content in idempotency on Ikoma's BlogHugoen-usFri, 28 Aug 2026 10:07:45 +0900https://blog.yusukeikoma.com/posts/exactly-once-delivery-idempotency-and-backoff/Fri, 28 Aug 2026 10:07:45 +0900https://blog.yusukeikoma.com/posts/exactly-once-delivery-idempotency-and-backoff/When a request times out, the client cannot tell whether the request or only its acknowledgement was lost. This is why exactly-once delivery cannot be built, and why effectively-once processing is at-least-once delivery plus a receiver that deduplicates. A runnable experiment with a flaky network, the bug that still duplicates 89 of 200 requests, an atomic dedupe store, and a jitter simulation.https://blog.yusukeikoma.com/posts/one-open-admission/Wed, 12 Aug 2026 10:27:31 +0900https://blog.yusukeikoma.com/posts/one-open-admission/Controlling distributed task starts with one unfinished admission per workspace surface, a fixed destination, and idempotent retries during machine outages.