我正在使用以下代码来同步 goroutine。最近在调查一个错误时，我发现下面的代码并不总是有效。大约五分之一的失败。频道quit在我之前收到消息out频道。我能够在我的本地（不是在 go-playground）和 k8s 环境中一致地重现这个问题。作为一种解决方法，我现在使用sync.Map同步。

有没有办法修复下面的代码？

package main

import (
    "fmt"
    "io/ioutil"
    "log"
    "os"
    "path"
    "sync"
    "sync/atomic"
    "time"
)

func main() {
    //test setup
    filePaths := []string{
        path.Join(os.TempDir(), fmt.Sprint("f1-", time.Now().Nanosecond())),
        path.Join(os.TempDir(), fmt.Sprint("f2-", time.Now().Nanosecond())),
        path.Join(os.TempDir(), fmt.Sprint("f3-", time.Now().Nanosecond())),
        path.Join(os.TempDir(), fmt.Sprint("f4-", time.Now().Nanosecond())),
        path.Join(os.TempDir(), fmt.Sprint("f5-", time.Now().Nanosecond())),
        path.Join(os.TempDir(), fmt.Sprint("f6-", time.Now().Nanosecond())),
    }
    for _, filePath := range filePaths {
        f, err := os.OpenFile(filePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0600)
        if err != nil {
            log.Fatal(err)
        }
        _, err = f.WriteString("There are many variations of passages of Lorem Ipsum available, but the majority have suffered alteration in some form, by injected humour, or randomised words which don't look even slightly believable. If you are going to use a passage of Lorem Ipsum, you need to be sure there isn't anything embarrassing hidden in the middle of text. All the Lorem Ipsum generators on the Internet tend to repeat predefined chunks as necessary, making this the first true generator on the Internet. It uses a dictionary of over 200 Latin words, combined with a handful of model sentence structures, to generate Lorem Ipsum which looks reasonable. The generated Lorem Ipsum is therefore always free from repetition, injected humour, or non-characteristic words etc.")
        if err != nil {
            log.Fatal(err)
        }
        err = f.Close()
        if err != nil {
            log.Fatal(err)
        }
    }
    for  {
        responses, err := getContents(filePaths)
        if err != nil {
            log.Fatal(err)
        }
        if len(responses) != len(filePaths) {
            log.Fatalf("Responses Does not Match, need %d Got %d",len(filePaths), len(responses))
        }
        time.Sleep(1 * time.Second)
    }

}


func  getContents(fileNames []string) ([][]byte, error) {
    wg := sync.WaitGroup{}
    var responseBytes [][]byte
    out := make(chan []byte, 10)
    defer close(out)
    quit := make(chan int)
    var opsFileRead uint64
    var opsChannelGot uint64
    defer close(quit)
    go func() {
        for {
            select {
            case bts := <-out:
                if len(bts) > 0 {
                    atomic.AddUint64(&opsChannelGot, 1)
                    responseBytes = append(responseBytes, bts)
                }
                break
            case <-quit:
                fmt.Printf("I quit, i read %d, i got %dn", opsFileRead, opsChannelGot)
                return
            }
        }
    }()
    for _, fileName := range fileNames {
        wg.Add(1)
        go func(fName string, out chan []byte, wg *sync.WaitGroup) {
            defer wg.Done()
            data, err := ioutil.ReadFile(fName)
            if err != nil {
                log.Fatal(err)
            }
            out <- data
            atomic.AddUint64(&opsFileRead, 1)
        }(fileName, out, &wg)
    }
    wg.Wait()
    quit <- 1
    return responseBytes, nil
}

回答

out := make(chan []byte)

func getContents(fileNames []string) ([][]byte, error) {
    wg := sync.WaitGroup{}
    var responseBytes [][]byte
    out := make(chan []byte)
    var opsFileRead uint64
    var opsChannelGot uint64

    for _, fileName := range fileNames {
        wg.Add(1)
        go func(fName string, out chan []byte, wg *sync.WaitGroup) {
            defer wg.Done()
            data, err := ioutil.ReadFile(fName)
            if err != nil {
                log.Fatal(err)
            }
            out <- data
            atomic.AddUint64(&opsFileRead, 1)
        }(fileName, out, &wg)
    }

    // Close out after workers are done.
    go func() {
        wg.Wait()
        close(out)
    }()

    // Loop over outputs until done.
    for bts := range out {
        if len(bts) > 0 {
            atomic.AddUint64(&opsChannelGot, 1)
            responseBytes = append(responseBytes, bts)
        }
    }

    fmt.Printf("I quit, i read %d, i got %dn", opsFileRead, opsChannelGot)

    return responseBytes, nil
}