AI-Generated Cache & Rate Limiting Code: Hidden Concurrency Bugs Exposed by Stress Testing
This postmortem reveals how AI-generated Redis caching and rate limiting code for a real estate query API passed unit tests but collapsed under 200 concurrent requests, exposing critical flaws in Bloom filter synchronization, mutex lock recursion, random expiration logic, and non-atomic rate limiting — with fixes using Redisson, Lua scripts, and async hot-key refresh.
