Golang program where time.After didn'trigger

main.go

package main

import (
	"fmt"
	"time"
)

func main() {
	ticker := time.NewTicker(5 * time.Second)
	for {
		select {
		case <-time.After(30 * time.Second):
			// after 5 minutes, it will stop this anyway
			fmt.Println("stop 5 m")
			ticker.Stop()
			return
		case <-ticker.C:
			// this will check flag every 5s
			fmt.Println("stop 5s")
		}
	}
}