The Go race detector doesn’t actually find data races; it detects potential data races by observing memory access patterns.
Let’s see it in action. Imagine this simple Go program:
package main
import (
"fmt"
"sync"
"time"
)
var counter int
func main() {
var wg sync.WaitGroup
wg.Add(2)
go func() {
defer wg.Done()
counter++
}()
go func() {
defer wg.Done()
counter++
}()
wg.Wait()
fmt.Println("Final counter:", counter)
}
This code looks innocent enough. We have a shared counter variable, and two goroutines incrementing it concurrently. We use sync.WaitGroup to ensure both goroutines finish before we print the final value.
If you run this program normally (go run main.go), you’ll likely see Final counter: 2. But if you run it with the race detector enabled:
go run -race main.go
You’ll get output similar to this:
==================
WARNING: DATA RACE DETECTED in
Write at 0x10a675c by goroutine 7:
main.main.func1()
/path/to/your/project/main.go:14 +0x39
Previous write at 0x10a675c by goroutine 8:
main.main.func2()
/path/to/your/project/main.go:20 +0x39
Goroutine 7 (running)
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