trick

m.go

// A cancellable job runner prototype.
package main

import (
	"fmt"
	"math/rand"
	"time"
)

func worker(id int, cancel chan interface{}, done chan int) {

	d := rand.Intn(10)
	fmt.Printf("%d will take %d secs\n", id, d)
	bgWorkChan := func(wait time.Duration) chan interface{} {
		c := make(chan interface{})
		go func() {
			time.Sleep(wait)
			c <- nil
		}()
		return c
	}(time.Duration(d) * time.Second)

	for {
		select {
		case <-cancel:
			fmt.Printf("%d cancel received\n", id)
			fmt.Printf("work should be cancelled\n")
			return
		case <-bgWorkChan:
			fmt.Printf("%d job is finished\n", id)
			done <- id
			return
		}
	}
}

func main() {
	rand.Seed(time.Now().Unix())

	workerCount := 5
	c := make(chan interface{}, workerCount)
	respChan := make(chan int)
	for i := 0; i < workerCount; i++ {
		go worker(i, c, respChan)
	}

	id := <-respChan
	fmt.Printf("worker %d has finished, cancel other\n", id)
	for i := 0; i < workerCount; i++ {
		c <- i
	}

	time.Sleep(1 * time.Second)
}