Get goroutine id for debugging

goroutine-id.go

package main

import (
	"fmt"
	"runtime"
	"strings"
	"sync"
)

// Goid gets goroutine ID. Only used for debugging purpose.
//
// Refs:
//   - https://groups.google.com/g/golang-nuts/c/Nt0hVV_nqHE/m/bwndAYvxAAAJ
//   - https://play.golang.org/p/OeEmT_CXyO
//   - https://gist.github.com/metafeather/3615b23097836bc36579100dac376906
//   - https://gist.github.com/afriza/22d096b9cdec2a4b2d2d03ab6b9a6c32
func Goid() string {
	var buf [64]byte
	n := runtime.Stack(buf[:], false)
	s := string(buf[:n])
	// Sample value for s:
	// "goroutine 25 [running]:\nmain.Goid()\n\t/tmp/sandbox3231773321/prog"
	s = strings.TrimPrefix(s, "goroutine ")
	s, _, found := strings.Cut(s, " ")
	if !found { // just in case, fallback to strings.Cut() + strings.Fields()
		s, _, _ = strings.Cut(s, "\n")
		s = strings.Fields(s)[0]
	}
	return s
}

func main() {
	fmt.Println("main", Goid())
	var wg sync.WaitGroup
	for i := 0; i < 10; i++ {
		i := i
		wg.Add(1)
		go func() {
			defer wg.Done()
			fmt.Println(i, Goid())
		}()
	}
	wg.Wait()
}