stop_goroutines.go

package main

import (
	"fmt"
	"sync"
	"time"
)

func main() {
	done := make(chan struct{})

	var wg sync.WaitGroup

	for i := 0; i < 4; i++ {
		go func(id int, done chan struct{}, waiter *sync.WaitGroup) {
			for {
				fmt.Printf("#%d running\n", id)
				time.Sleep(100 * time.Millisecond)
				select {
				case _ = <-done:
					fmt.Printf("#%d exitting.\n", id)
					wg.Done()
					return
				default:
				}
			}
		}(i, done, &wg)
	}

	wg.Add(4)

	time.Sleep(1000 * time.Millisecond)
	close(done)
	wg.Wait()
}