php小編小新帶來了一篇關於使用goroutine建構Zip的技巧文章。在這篇文章中，我們將了解如何利用goroutine並發執行Zip操作，以提高程式的效率。此外，我們還將討論切片超出範圍的問題，並介紹如何使用容量為4096的切片來解決這個問題。無論你是初學者還是有經驗的開發者，本文都將幫助你更好地理解和應用與goroutine和切片相關的知識。讓我們一起來探索吧！
問題內容
我正在嘗試透過新增 goroutine 來處理每個必須存檔的檔案來改進建立 zip 的函數。
但最終卻以恐慌告終
panic：運行時錯誤：切片超出範圍[4126：4096]
目標目錄包含 190 個檔案（500 mo）。
我實在不懂出了什麼問題
先感謝您的幫助
功能：
func buildarchive() error {
var files []string
err := filepath.walk("/tmp/dir-to-zip", func(filepath string, info os.fileinfo, err error) error {
if info.isdir() {
return nil
}
if err != nil {
fmt.println(err)
return err
}
files = append(files, filepath)
return nil
})
if err != nil {
return err
}
bundle, err := os.create("/tmp/archive.zip")
if err != nil {
return err
}
bundlewriter := zip.newwriter(bundle)
var wg sync.waitgroup
wg.add(len(files))
for _, filepath := range files {
go func(filepath string) {
defer wg.done()
relpath := strings.trimprefix(filepath, fmt.sprintf("%v/", filepath.dir("/tmp/dir-to-zip")))
bundlefile, err := bundlewriter.create(relpath)
if err != nil {
fmt.println(err)
}
fsfile, err := os.open(filepath)
if err != nil {
fmt.println(err)
}
_, err = io.copy(bundlefile, fsfile)
if err != nil {
fmt.println(err)
}
}(filepath)
}
wg.wait()
err = bundlewriter.close()
if err != nil {
return err
}
return nil
}登入後複製
錯誤發生在這裡：
_, err = io.copy(bundlefile, fsfile)
if err != nil {
fmt.println(err)
}登入後複製
堆疊追蹤：
goroutine 48 [running]:
bufio.(*Writer).Write(0xc00002a100, {0xc00041a400?, 0x3d?, 0xc00041a400?})
/usr/local/go/src/bufio/bufio.go:670 +0x1c8
archive/zip.(*countWriter).Write(0xc00000c138, {0xc00041a400?, 0x3d?, 0x4afa20?})
/usr/local/go/src/archive/zip/writer.go:601 +0x2e
io.WriteString({0x4e7538, 0xc00000c138}, {0xc0000212c9, 0x3d})
/usr/local/go/src/io/io.go:314 +0x91
archive/zip.writeHeader({0x4e7538, 0xc00000c138}, 0xc000220090)
/usr/local/go/src/archive/zip/writer.go:422 +0x5ec
archive/zip.(*Writer).CreateHeader(0xc0000760a0, 0xc00021e1b0)
/usr/local/go/src/archive/zip/writer.go:378 +0x797
archive/zip.(*Writer).Create(0x4e7698?, {0xc0000212c9, 0x3d})
/usr/local/go/src/archive/zip/writer.go:223 +0x6c
main.BuildArchive.func2({0xc0000212c0, 0x46})
/home/simba/go/src/foobar/main.go:79 +0x1c5
created by main.BuildArchive
/home/simba/go/src/foobar/main.go:73 +0x5aa
panic: runtime error: slice bounds out of range [:4126] with capacity 4096
goroutine 6 [running]:
bufio.(*Writer).Flush(0xc00002a100)
/usr/local/go/src/bufio/bufio.go:634 +0x171
bufio.(*Writer).Write(0xc00002a100, {0xc0001b4200?, 0xc000199b20?, 0xc000199b20?})
/usr/local/go/src/bufio/bufio.go:672 +0xd8
archive/zip.(*countWriter).Write(0xc00000c138, {0xc0001b4200?, 0x0?, 0xc000199b40?})
/usr/local/go/src/archive/zip/writer.go:601 +0x2e
archive/zip.(*countWriter).Write(0xc000220018, {0xc0001b4200?, 0xc0001b02c0?, 0xc0001b02f0?})
/usr/local/go/src/archive/zip/writer.go:601 +0x2e
compress/flate.(*huffmanBitWriter).write(...)
/usr/local/go/src/compress/flate/huffman_bit_writer.go:136
compress/flate.(*huffmanBitWriter).writeCode(0xc0001b41e0?, {0x6000?, 0x22?})
/usr/local/go/src/compress/flate/huffman_bit_writer.go:347 +0xe5
compress/flate.(*huffmanBitWriter).writeTokens(0xc0001b41e0, {0xc002558000, 0x4001, 0x403f800000403f?}, {0xc0001aa900, 0x11e, 0x108129000000000f?}, {0xc0001ac100, 0x1e, 0x1e})
/usr/local/go/src/compress/flate/huffman_bit_writer.go:583 +0xb9
compress/flate.(*huffmanBitWriter).writeBlock(0xc0001b41e0, {0xc002558000?, 0x20?, 0xd79?}, 0x0, {0x0, 0x0, 0x0})
/usr/local/go/src/compress/flate/huffman_bit_writer.go:495 +0x490
compress/flate.(*compressor).writeBlock(0xc0005a2000, {0xc002558000?, 0xc000032f00?, 0xc000199d28?}, 0x47739b?)
/usr/local/go/src/compress/flate/deflate.go:170 +0x9c
compress/flate.(*compressor).deflate(0xc0005a2000)
/usr/local/go/src/compress/flate/deflate.go:509 +0x59b
compress/flate.(*compressor).write(0xc0005a2000, {0xc00256a000?, 0x8000, 0xf311b6fd?})
/usr/local/go/src/compress/flate/deflate.go:554 +0x82
compress/flate.(*Writer).Write(...)
/usr/local/go/src/compress/flate/deflate.go:712
archive/zip.(*pooledFlateWriter).Write(0xc00020c040?, {0xc00256a000?, 0x8000?, 0x4af140?})
/usr/local/go/src/archive/zip/register.go:51 +0xc5
archive/zip.(*countWriter).Write(...)
/usr/local/go/src/archive/zip/writer.go:601
archive/zip.(*fileWriter).Write(0xc000222000, {0xc00256a000, 0x8000, 0x8000})
/usr/local/go/src/archive/zip/writer.go:533 +0x97
io.copyBuffer({0x4e7558, 0xc000222000}, {0x4e7678, 0xc0001f8008}, {0x0, 0x0, 0x0})
/usr/local/go/src/io/io.go:428 +0x204
io.Copy(...)
/usr/local/go/src/io/io.go:385
main.BuildArchive.func2({0xc00001c0c0, 0x35})
/home/simba/go/src/foobar/main.go:89 +0x385
created by main.BuildArchive
/home/simba/go/src/foobar/main.go:73 +0x5aa
exit status 2登入後複製
解決方法
zip.Writer 並發使用不安全。您啟動多個 goroutine，每個 goroutine 建立並寫入 zip 條目（檔案）。
Writer.Create() 記錄：
建立使用提供的名稱將檔案加入 zip 檔案。它傳回一個 Writer，文件內容應寫入其中。
[...] 在下次呼叫 Create、CreateHeader 或 Close 之前，必須將檔案內容寫入 io.Writer。
您不能同時建立 zip。每個zip 條目的io.Writers 寫入相同的底層檔案（或一般情況下相同的io.Writer），即使您的應用程式沒有出現恐慌或崩潰，產生的zip 檔案也可能無效。
以上是使用 goroutine 建構 Zip，切片超出範圍，容量為 4096的詳細內容。更多資訊請關注PHP中文網其他相關文章！
