Golang Goroutine 错误“所有 goroutines 都在休眠 - 死锁！”

Question

我正在尝试制作一个代码，以从文件夹链接我的所有文件进行扫描，并根据他的内容和他的姓名使用正则表达式按他的大小制作“前 10 名”。文件。通过它的内容，我用 goroutines 制作频道，但我不明白为什么每次我的 goroutines 都被锁定。这是我的代码：

package main

import (
    "flag"
    "fmt"
    "io/ioutil"
    "regexp"
    "runtime"
    "sort"
    "sync"
    "time"
)

var rName = ".php"
var rContent = "php"
var maxSize, minSize int64
var files_ten []File

func main() {
    start := time.Now()

    channelOne := make(chan File)
    channelTwo := make(chan File)

    var wg sync.WaitGroup
    var path string
    flag.StringVar(&path, "path", "", "Path to folder")
    flag.Parse()
    fmt.Println("Path=", path)

    for i := 0; i < runtime.NumCPU(); i++ {
        go check(channelOne, channelTwo, &wg)
    }

    go top10(channelTwo, &wg)

    wg.Wait()

    getFolder(path, channelOne, &wg)

    fmt.Println("top 10", files_ten)
    t := time.Now()
    current := t.Sub(start)
    fmt.Println(current)

}

type File struct {
    Size int64
    Name string
    Path string
}

func (this File) GetSize() int64 {
    return this.Size
}

func getFolder(path string, channelOne chan File, wg *sync.WaitGroup) {
    folder, err := ioutil.ReadDir(path)

    if err != nil {
        fmt.Println("Error:", err)
        return
    }

    for _, data := range folder {
        if data.IsDir() {
            var newFolder string = path + data.Name() + "/"
            getFolder(newFolder, channelOne, wg)
        } else {
            wg.Add(1)
            channelOne <- File{Size: data.Size(), Name: data.Name(), Path: path}
        }
    }
}

func check(channelOne chan File, channelTwo chan File, wg *sync.WaitGroup) {
    for {
        file := <-channelOne
        rName := regexp.MustCompile(rName)

        maxSize = 10000
        minSize = 0

        if rName.MatchString(file.Name) {
            if file.Size <= maxSize && file.Size >= minSize {
                f, err := ioutil.ReadFile(file.Path + "/" + file.Name)

                if err != nil {
                    fmt.Println("Error:", err)
                    return
                }
                rContent := regexp.MustCompile(rContent)
                if rContent.MatchString(string(f)) {
                    channelTwo <- file
                } else {
                    wg.Done()
                }
            } else {
                wg.Done()
            }
        } else {
            wg.Done()
        }
    }
}

func sortFilesFromBiggestToLowerSize(arrayFile []File) []File {
    sort.Slice(arrayFile, func(i, j int) bool {
        return arrayFile[i].Size > arrayFile[j].Size
    })
    return arrayFile
}

func top10(channelTwo chan File, wg *sync.WaitGroup) []File {
    for {
        f := <-channelTwo

        if len(files_ten) == 10 {
            if f.Size > files_ten[0].Size || f.Size >
                files_ten[len(files_ten)-1].Size {
                files_ten = files_ten[:len(files_ten)-1]
                files_ten = append(files_ten, f)
                return sortFilesFromBiggestToLowerSize(files_ten)
            }
        } else {
            sortFilesFromBiggestToLowerSize(files_ten)
            return append(files_ten, f)
        }
        wg.Done()
        return files_ten
    }
}

这是每次编译时的错误：

go run filebysize.go --path=C:/wamp64/www/symfony/init/cours1/
Path= C:/wamp64/www/symfony/init/cours1/
fatal error: all goroutines are asleep - deadlock!

goroutine 1 [chan send]:
main.getFolder(0xc04210a3c0, 0x3d, 0xc04204c0c0, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:72 +0x28a
main.getFolder(0xc04210a200, 0x32, 0xc04204c0c0, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:69 +0x151
main.getFolder(0xc04200e6c0, 0x26, 0xc04204c0c0, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:69 +0x151
main.getFolder(0xc042051f57, 0x22, 0xc04204c0c0, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:69 +0x151
main.main()
    C:/Users/Sahra/Documents/go/display/filebysize.go:37 +0x2e0

goroutine 19 [chan send]:
main.check(0xc04204c0c0, 0xc04204c120, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:95 +0x2ec
created by main.main
    C:/Users/Sahra/Documents/go/display/filebysize.go:32 +0x26d

goroutine 20 [chan send]:
main.check(0xc04204c0c0, 0xc04204c120, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:95 +0x2ec
created by main.main
    C:/Users/Sahra/Documents/go/display/filebysize.go:32 +0x26d

goroutine 21 [chan send]:
main.check(0xc04204c0c0, 0xc04204c120, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:95 +0x2ec
created by main.main
    C:/Users/Sahra/Documents/go/display/filebysize.go:32 +0x26d

goroutine 22 [chan send]:
main.check(0xc04204c0c0, 0xc04204c120, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:95 +0x2ec
created by main.main
    C:/Users/Sahra/Documents/go/display/filebysize.go:32 +0x26d

goroutine 23 [chan send]:
main.check(0xc04204c0c0, 0xc04204c120, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:95 +0x2ec
created by main.main
    C:/Users/Sahra/Documents/go/display/filebysize.go:32 +0x26d

goroutine 24 [chan send]:
main.check(0xc04204c0c0, 0xc04204c120, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:95 +0x2ec
created by main.main
    C:/Users/Sahra/Documents/go/display/filebysize.go:32 +0x26d

goroutine 25 [chan send]:
main.check(0xc04204c0c0, 0xc04204c120, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:95 +0x2ec
created by main.main
    C:/Users/Sahra/Documents/go/display/filebysize.go:32 +0x26d

goroutine 26 [chan send]:
main.check(0xc04204c0c0, 0xc04204c120, 0xc04204e210)
    C:/Users/Sahra/Documents/go/display/filebysize.go:95 +0x2ec
created by main.main
    C:/Users/Sahra/Documents/go/display/filebysize.go:32 +0x26d
exit status 2

Answer 1

您正尝试在channelOne 上发送，但直到 wg.Done 之后才从其中读取任何内容，因此出现了死锁：尝试发送给它的例程必须等到可以接收某些东西，而这永远不会发生。

另外，您的 WaitGroup 使用已关闭；您应该在启动每个要等待的 goroutine 之前调用 Add，然后在 goroutine 结束时调用 Done。单个goroutine不应在循环中调用Add或Done，如果没有关联的Add调用，则goroutine不应调用Done。

看起来您有多个永远不会退出的for 循环；他们没有条件也没有breaks。

您还可以更简单地循环频道。您可以替换如下结构：

for {
    file := <-channelOne

用更简单的：

for file := range channelOne {

这还有一个额外的好处，即当您覆盖的通道关闭时，循环将退出，允许您使用关闭通道作为消费者可以停止的信号。