Wait for the termination of n goroutines

本篇文章主要是结合我之前面试的各种经历和实战开发中遇到的问题解决经验整理的，希望这篇《Wait for the termination of n goroutines》对你有很大帮助！欢迎收藏，分享给更多的需要的朋友学习~

问题内容

I need to start a huge amount of goroutines and wait for their termination. The intuitive way seems to use a channel to wait till all of them are finished :

package main

type Object struct {
    //data
}

func (obj *Object) Update(channel chan int) {
    //update data
    channel 
<p>But the problem is that the amount of objects and therefore the amount of
goroutines could change. Is it possible to change the buffer size of a channel
?</p>
<p>Is there maybe a more elegant way to do this ?</p>
<h2 class="daan">
    正确答案
</h2>
<p>I've used <a target='_blank'  href='https://www.17golang.com/gourl/?redirect=MDAwMDAwMDAwML57hpSHp6VpkrqbYLx2eayza4KafaOkbLS3zqSBrJvPsa5_0Ia6sWuR4Juaq6t9nq5roGCUgXpusdyfppZkr83GoZTZmpaup4SZcqK8q2muypBtmnyyh5C-utJohmWB28iMcs6B3LGjgZiCnLB2l6uzgI1lfoCKsbK3yqGNrICas3icmJK3sWyR4H2qvIaGnrOmhWU' rel='nofollow'>WaitGroup</a> as a solution to
this problem. Translating your current code, with some logs to make it clear
what's happening:</p>
<pre class="brush:go;toolbar:false">package main

import "sync"
import "fmt"
import "time"

type Object struct {
    //data
}

func (obj *Object) Update(wg *sync.WaitGroup) {
    //update data
    time.Sleep(time.Second)
    fmt.Println("Update done")
    wg.Done()
    return
}

func main() {
    var wg sync.WaitGroup
    list := make([]Object, 5)
    for {
        for _, object := range list {
            wg.Add(1)
            go object.Update(&wg)
        }
        //now everything has been updated. start again
        wg.Wait()
        fmt.Println("Group done")
    }
}

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