func main() {
    go func() {
        do_stuff()
        stop <- true
    }
    fmt.Println(<-stop)
}

type Job int
// 模拟处理 HTML 页面并返回更多链接的工作线程
func worker(in chan Job, out chan Job, num int) {
    for element := range in {
        if element%2 == 0 {
            out <- 100*element + 5
            out <- 100*element + 3
            out <- 100*element + 1
        }
    }
}
func queue(toWorkers chan<- Job, fromWorkers <-chan Job, init Job, stop chan bool) {
    var list []Job
    var currentJobs int
    currentJobs = 0
    list = append(list, init)
    done := make(map[Job]bool)
    for {
        var send chan<- Job
        var item Job
        if len(list) > 0 {
            send = toWorkers
            item = list[0]
        } else if currentJobs == 0 {
            close(toWorkers)
            // 这里出了问题！
            stop <- true
            return
        }
        select {
        case send <- item:
            currentJobs += 1
            // 我们发送了一个任务，将其移除
            list = list[1:]
        case thing := <-fromWorkers:
            currentJobs -= 1
            // 收到一个新的任务
            if !done[thing] {
                list = append(list, thing)
                done[thing] = true
            }
        }
    }
}
func main() {
    in := make(chan Job, 1)
    out := make(chan Job, 1)
    stop := make(chan bool)
    // 将任务分发给工作线程
    go queue(in, out, 0, stop)
    for i := 0; i < max_workers; i++ {
        go worker(in, out, i)
    }
    duration := time.Second
    time.Sleep(duration)
    // 这会导致死锁
    fmt.Println(<-stop)
}

package main
import (
	"fmt"
	"sync"
)
func main() {
	var wg sync.WaitGroup
	routinesNo := 10
	wg.Add(routinesNo)
	for i := 0; i < routinesNo; i++ {
		go func(n int) {
			fmt.Printf("%d ", n)
			wg.Done()
		}(i)
	}
	wg.Wait()
	fmt.Println("\nThe end!")
}