Book: The Complete Guide to Go Programming Also by me: Thinking in Go (2-book series) — Complete Guide to Go Programming + Hexagonal Architecture in Go My project: Hermes IDE | GitHub — an IDE for developers who ship with Claude Code and other AI coding tools Me: xgabriel.com | GitHub The first time you see WARNING: DATA RACE in your terminal you scroll. Wall of stack frames, two columns of "Read at" and "Previous write at", goroutine IDs that mean nothing yet, a creation stack at the bottom. The output is dense on purpose. The detector is showing you everything it knows so you can reconstruct the interleaving that produced the race. Race reports come in a small number of shapes. Once you have read a few, they collapse into patterns. This post is about three: a read/write race on a shared map, a closure-over-loop-variable race, and a data race carried by an interface fat-pointer. Each looks similar in the report and needs a different fix. The detector itself is the Go port of ThreadSanitizer .…