goroutine 从具有动态循环的通道读取等待组在返回之前被重用

Question

我正在开发一个小型实用程序，它需要迭代动态范围内的项目（可以是 100 或 100000）并将项目放入通道中。从该通道，另一个函数读取项目并分别对每个项目进行一些处理。我正在尝试使用 sync.WaitGroup 来确保我的实用程序不会在处理完频道中的所有项目之前退出。由于我对频道和等待组还很陌生，所以我遇到了一个错误 panic: sync: WaitGroup is reused before previous Wait has returned

https://play.golang.org/p/nMw3END_9qw

package main

import (
    "fmt"
    "github.com/dchest/uniuri"
    "math/rand"
    "sync"
    "time"
)

var wg sync.WaitGroup
var count = 0

func printMe(msg string) {
    time.Sleep(1 * time.Second)
    fmt.Println(count, msg)
}

func makeMePrint(ch chan string) {
    for s := range ch {
        count++
        wg.Add(1)
        printMe(s)
        wg.Done()
    }

}

func writePrint(ch chan<- string) {
    fmt.Println("Starting to insert data in channel")
    for i := 1; i <= rand.Intn(30); i++ {
        s := uniuri.New()
        ch <- s
    }
    fmt.Println("We are done inserting all data in the channel")
    close(ch)
}

func main() {

    var ch = make(chan string)

    go writePrint(ch)
    go makeMePrint(ch)
    time.Sleep(1 * time.Second)
    wg.Wait()
}

这是我正在研究的主要思想（不是确切的代码，而是具有相同数量功能的完全相同的体系结构）。

如何确保实用程序仅在通道中的所有项目都是进程时才退出。

感谢任何帮助。

Answer 1

我终于让它工作了。

package main

import (
    "fmt"
    "github.com/dchest/uniuri"
    "math/rand"
    "sync"
    "time"
)

var count = 0

func printMe(msg string) {
    time.Sleep(1 * time.Second)
    fmt.Println(count, msg)
}

func makeMePrint(wg *sync.WaitGroup, ch chan string) {
    wg.Add(1)
    defer wg.Done()

    for s := range ch {
        count++
        printMe(s)

    }

}

func writePrint(wg *sync.WaitGroup, ch chan<- string) {
    wg.Add(1)
    defer wg.Done()

    fmt.Println("Starting to insert data in channel")
    for i := 1; i <= rand.Intn(30); i++ {
        s := uniuri.New()
        ch <- s
    }
    fmt.Println("We are done inserting all data in the channel")
    close(ch)
}

func main() {
    wg := &sync.WaitGroup{}
    var ch = make(chan string)

    go writePrint(wg, ch)
    go makeMePrint(wg, ch)
    time.Sleep(1 * time.Second)
    wg.Wait()
}

goroutine 从具有动态循环的通道读取等待组在返回之前被重用

goroutine reading from channel with dynamic loop getting waitgroup is reused before previous was has returned

channel

go

goroutine