go routine leak

go_routine_leak.go

package main

import (
	"fmt"
	"log"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"
)

func main() {
	log.Println("running")

	printStack()

	//	wg := sync.WaitGroup{}
	//	wg.Add(2)
	go func(wg *sync.WaitGroup) {
		//		defer wg.Done()
		go func() {
			for {
				time.Sleep(1 * time.Second)
				log.Println("sub 2: running")
			}
		}()

		count := 1
		for {
			time.Sleep(1 * time.Second)
			log.Println("sub 1: running")
			count++
			if count > 3 {
				log.Println("sub 1: done")
				printStack()
				return
			}
		}
		//	}(&wg)
	}(nil)

	printStack()

	//wg.Wait()

	buf := make([]byte, 0, 0x1<<8)
	fmt.Scan(&buf)

	printStack()

	log.Println("done")
}

func printStack() {
	buf := make([]byte, 2<<20)
	buf = buf[:runtime.Stack(buf, true)]
	log.Printf("stack: %v", string(buf))

	for _, g := range strings.Split(string(buf), "\n\n") {
		printGoroutineID(g)
	}
}

func printGoroutineID(g string) {
	sl := strings.SplitN(g, "\n", 2)
	if len(sl) != 2 {
		log.Printf("error parsing stack: %q", g)
	}
	h := strings.SplitN(sl[0], " ", 3)
	if len(h) < 3 {
		log.Printf("error parsing stack header: %q", sl[0])
	}
	id, err := strconv.ParseUint(h[1], 10, 64)
	if err != nil {
		log.Printf("error parsing goroutine id: %s", err)
	}
	log.Printf("goroutine id: %v", id)
}