#single-flight

A second-level hotspot KV running on Cloudflare Workers (starting at $5/month): multi-region load testing pushed the read path past 860K RPS with zero worker errors, while the load generators hit their bottleneck first. This article explains its design, the full investigation of two real incidents (the first time we thought we had fixed it; the second time we found the real root cause: reads and writes were squeezed into the same queue of the same single-threaded object), and the final solution: separate reads from writes, plus redefining what “strong consistency” actually means.