The Go Programming Language

9.6 The Race Detector

Even with the greatest of care, it’s all too easy to make concurrency mistakes. Fortunately, the Go runtime and toolchain are equipped with a sophisticated and easy-to-use dynamic analysis tool, the race detector.

Just add the -race flag to your go build, go run, or go test command. This causes the compiler to build a modified version of your application or test with additional instrumentation that effectively records all accesses to shared variables that occurred during execution, along with the identity of the goroutine that read or wrote the variable. In addition, the modified program records all synchronization events, such as go statements, channel operations, and calls to (*sync.Mutex).Lock, (*sync.WaitGroup).Wait ...