How an External API Nearly Brought Down Our Service: Adopting Virtual Threads
Network I/O was blocking threads. JDK 21 virtual threads fixed that, then pinning and overwhelming showed up. How each one was handled.
Blog
Nexters 27th Cohort Retrospective: Experiments Over Theory, and the Users Had the Answers
As PM of Loopy in Nexters 26, I chased scenarios in my head, not users. In cohort 27 I joined Emotia, an AI for exploring emotions, as a backend developer.
Solving a Concurrency Problem with a Single UPDATE
1,000 people request 100 items at once. How a single UPDATE gives one to exactly 100 of them, instead of the locks usually proposed for a first-come event.
Solving Distributed Cache Synchronization with Redis Pub/Sub
Loading 40–60 delivery plans per screen from an external API was slow. Redis and local caches made it 50–100x faster, and Redis Pub/Sub kept servers in sync.
Why Removing @Transactional Doubled Performance in Production
@Transactional(readOnly = true) is supposed to speed Spring up by turning off dirty checking. Elastic APM showed extra JDBC calls that made it slower.