panic：运行时错误：当并行作为goroutine运行时，slice限制超出范围

本文介绍了panic：运行时错误：当并行作为goroutine运行时，slice限制超出范围的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 限时删除！！ 我将一个函数作为一个goroutine调用，并使用一个WaitGroup来阻止共享扫描器在完成之前关闭。 myfunc（）函数迭代文件。我想记忆映射这个文件并在所有goroutine之间共享它，而不是每次都有从磁盘读取的I / O chokepoint。有人告诉我，这种方法可以解决另一个问题的答案。然而，虽然这个功能独立运行，但它不是兼职工作。我收到错误： panic：运行时错误：切片范围超出范围 但错误是当我调用 Scan（）方法时（不在片上）这是令人困惑的。 这是一个MWE： //包装声明;进口; yada yada //实际尺寸图更有意义，这仅仅是MWE var Sizes = map [int] string { 10：Ten， 20：Twenty， 30：三十， 40：四十，} 类型FileScanner结构{ io.Closer * bufio.Scanner } func main（）{ // ...验证存储在filePath变量中的文件的路径 filePath：=/path/to/file.txt //获取单词列表扫描器以便在goroutines之间共享 scanner：= getScannerPtr（&filePath） //为每个参数调用myfunc（）传递 var wg sync.WaitGroup $ b $ ch：= make（chan string） for _，param：= range os.Args [ 1：] { wg.Add（1） go myfunc（& param，scanner，ch） wg.Done（）} //打印从频道收到的范围为os.Args的结果[1：] { fmt.Println（< -ch）//打印从频道收到的数据ch } //在所有goroutines完成之前，不要关闭扫描器 wg.Wait（） defer scanner.Close（）} func getScannerPtr（filePath * string）* FileScanner {f，err：= os.Open（* filePath） if err！= nil { fmt.Fprint（os.Stderr， 错误打开文件\）恐慌（错误）} 扫描器：= bufio.NewScanner（f）返回& FileScanner {f，扫描器} $ b func myfunc（param * string，scanner * FileScanner，ch chan< -string）{ for scanner.Scan（）{ line：= strings.TrimSpace （scanner.Text（）） // ...使用行进行某些操作（只读） // ...访问共享执行此操作时的大小映射（只读） ch } } 认为这个问题是对共享大小映射的并发访问，但是它在 myfunc（）中移动（并且低效地重新声明/每次重新定义它）仍导致相同的错误，这与调用 Scan（）有关。我试图按照我收到的指导在这个答案中。 panic：运行时错误：切片边界超出范围 goroutine 6 [running]： bufio。（* Scanner）.Scan（0xc42008a000，0x80） /usr/local/go/src/bufio/scan.go:139+ 0xb3e main.crack（0xc42004c280,0xc42000a080,0xc42001c0c0） /Users/dan/go/src/crypto_ctf_challenge/main.go:113+ 0x288 由main.main创建 / Users /dan/go/src/crypto_ctf_challenge/main.go:81 + 0x1d8 退出状态2 go myfunc（& param，scanner，ch） $ b> 第113行是： .Scan（）{ 解决方案 code>扫描来源，它似乎不是threa d安全。您可以通过从扫描器中读取一个例程来解决这个问题，而其他任何例程都会消耗行并处理它们： func main（）{ // ...验证存放在filePath变量中的文件的路径 filePath：=/path/to/file.txt //获取单词列表扫描器以便在goroutines之间共享 scanner：= getScannerPtr（&filePath） defer scanner.Close（） //为每个传递的参数调用myfunc（） var wg sync.WaitGroup $ b $ ch：make（chan string） lines：= make（chan string）去func（）{ for scanner.Scan （）{ lines< - scanner.Text（）} close（lines）（） for _，param：= range os.Args [1：] { wg.Add（1） go myfunc（param，lines，ch） wg.Done（）} //打印从频道收到的范围为os.Args的结果[1：] { fmt.Println（&l t; -ch）//打印从频道接收到的数据ch } //在所有goroutines完成之前不关闭扫描器 wg.Wait（）} func myfunc（param string，chan [] byte，ch chan< -string）{ for line：= range lines { line = strings.TrimSpace（行） // ...用行（只读）执行某些操作 // ...访问共享执行操作时的大小映射（只读） ch } 另外请注意， 延迟函数中的最后一行;整个 defer 点就是在函数体内的某处调用它，并知道函数返回后会调用它。由于您使用 WaitGroup 来防止函数返回，直到完成扫描程序，所以您可以安全地推迟关闭。 I'm calling a function as a goroutine and using a WaitGroup to prevent closing a shared Scanner before they all finish. The myfunc() function iterates over a file. I wanted to memory-map this file and share it between all of the goroutines rather than have the I/O chokepoint of reading from disk each time. I was told that this approach would work in an answer to another question. However, while this function worked fine standalone, it's not working concurrently. I am receiving the error:panic: runtime error: slice bounds out of rangebut the error is when I call the Scan() method (not on a slice) which is confusing.Here is a MWE:// ... package declaration; imports; yada yada// the actual Sizes map is much more meaningful, this is just for the MWEvar Sizes = map[int]string { 10: "Ten", 20: "Twenty", 30: "Thirty", 40: "Forty",}type FileScanner struct { io.Closer *bufio.Scanner}func main() { // ... validate path to file stored in filePath variable filePath := "/path/to/file.txt" // get word list scanner to be shared between goroutines scanner := getScannerPtr(&filePath) // call myfunc() for each param passed var wg sync.WaitGroup ch := make(chan string) for _, param := range os.Args[1:] { wg.Add(1) go myfunc(&param, scanner, ch) wg.Done() } // print results received from channel for range os.Args[1:] { fmt.Println(<-ch) // print data received from channel ch } // don't close scanner until all goroutines are finished wg.Wait() defer scanner.Close()}func getScannerPtr(filePath *string) *FileScanner { f, err := os.Open(*filePath) if err != nil { fmt.Fprint(os.Stderr, "Error opening file\n") panic(err) } scanner := bufio.NewScanner(f) return &FileScanner{f, scanner}}func myfunc(param *string, scanner *FileScanner, ch chan<-string) { for scanner.Scan() { line := strings.TrimSpace(scanner.Text()) // ... do something with line (read only) // ... access shared Sizes map when doing it (read only) ch <- "some string result goes here" }}I originally thought the issue was concurrent access to the shared Sizes map, but moving it inside myfunc() (and inefficiently redeclaring/redefining it every time) still resulted in the same error, which has to do with calling Scan(). I'm attempting to follow the guidance I received in this answer.Here's the full stack trace of the panic:panic: runtime error: slice bounds out of rangegoroutine 6 [running]:bufio.(*Scanner).Scan(0xc42008a000, 0x80) /usr/local/go/src/bufio/scan.go:139 +0xb3emain.crack(0xc42004c280, 0xc42000a080, 0xc42001c0c0) /Users/dan/go/src/crypto_ctf_challenge/main.go:113 +0x288created by main.main /Users/dan/go/src/crypto_ctf_challenge/main.go:81 +0x1d8exit status 2Line 81 is:go myfunc(&param, scanner, ch)Line 113 is:for scanner.Scan() { 解决方案 Actually after review of the Scan source, it doesn't appear to be thread-safe. You can get around this by having one routine read off of the scanner, and any number of other routines consume lines and process them:func main() { // ... validate path to file stored in filePath variable filePath := "/path/to/file.txt" // get word list scanner to be shared between goroutines scanner := getScannerPtr(&filePath) defer scanner.Close() // call myfunc() for each param passed var wg sync.WaitGroup ch := make(chan string) lines := make(chan string) go func() { for scanner.Scan() { lines <- scanner.Text() } close(lines) }() for _, param := range os.Args[1:] { wg.Add(1) go myfunc(param, lines, ch) wg.Done() } // print results received from channel for range os.Args[1:] { fmt.Println(<-ch) // print data received from channel ch } // don't close scanner until all goroutines are finished wg.Wait()}func myfunc(param string, lines chan []byte, ch chan<-string) { for line := range lines { line = strings.TrimSpace(line) // ... do something with line (read only) // ... access shared Sizes map when doing it (read only) ch <- "some string result goes here" }}Also note that there's no point in defering the last line in a function; the whole point of defer is to call it somewhere in the body of the function and know it will be called after the function returns. Since you're using a WaitGroup to prevent the function returning until you're done with your scanner, you can safely defer the close immediately. 这篇关于panic：运行时错误：当并行作为goroutine运行时，slice限制超出范围的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 1403页，肝出来的..