Byungho ChoiSomeone who makes things work, and makes things
I close the distance between what people actually want and a system that actually runs. I believe the world belongs to the people who make things.
60+
SYSTEM DESIGN STUDY SESSIONS LED
677
BLOG POSTS · 150+ TECH ARTICLES
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MERGED INTO 14 UNRELATED CODEBASES
- Building and operating payment platform backends. Distributed transactions and concurrency are the daily subject
- 2026-08I took a lock and thirty people missed their coupon: what unique constraints and conditional writes really do
- 2026-07Reviewing my own paper: three things we get wrong about JPA performance
The series I am writing now. The full index of 677 posts is under writing. Posts are in Korean. as of 2026-08-23
Ep.7Compensation: the order was cancelled but the coupon never came backEp.6Boundaries: we added one order state and stores got overpaidEp.5Isolation: one slow thing stops everythingEp.4Unique IDs: when the clock runs backwardsEp.3DynamoDB: deleted items come backEp.2Rate Limiting: what to block, and where, when traffic floodsEp.1Rate Limiting: six algorithms taken apart, down to the Redis commands
CAREERPayments · mobility platforms8 case studies plus other work, written as situation, choice, outcome→
OSSNetty · Apache Maven · Spring Kafka · Redis19 merged upstream · Korea MSIT Minister's Award→
WRITINGTechnical article indexdebugging · design · infra, 677 posts (Korean)→
WORLD3D interactive annexthe same content as a game map · optional↗