package main

import (
	"context"
	"sync"
	"time"
)

func main() {
	ctx, cacnel := context.WithTimeout(context.Background(), time.Second*5)
	defer cacnel()
	wg := sync.WaitGroup{}
	go func() {
		defer func() {
			wg.Done()
			println("goroutine exit")
		}()
		select {
		case <-ctx.Done():
			println("context done")
			return
		}
	}()
	wg.Add(1)
	wg.Wait()
}