Spring-Boot

Rate limiting shows up in two places: your on-call rotation and your system design interview. Both reward the same thing — knowing which algorithm to pick, why, and what breaks at scale. This guide builds three working limiters in Spring Boot, each with tests: Fixed window — the simplest thing that works, hand-rolled. Token bucket — smooth, burst-friendly, via Bucket4j. Distributed sliding window — precise and shared across instances, on Redis with Lua. Then we close with the part interviews actually grade: how to talk through the tradeoffs. ...

Virtual threads can be one of the easiest throughput wins in a blocking Spring Boot application. The switch is one line: spring: threads: virtual: enabled: true But that line changes the concurrency model of the application. It does not make database queries faster, reduce API latency, or create more database connections. It makes waiting cheaper by allowing many request tasks to share a smaller number of carrier threads. ...