After the code optimization of golang Climbing Zhenai.com, the following error was reported after running. It took half an hour to find the reason. Record it here.
The code is like this:< /p>
There is an interface type Parser:
type Parser interface {Parser(contents []byte, url string) ParserResult Serialize() (funcName string, args interface{ })}
There is a FuncParser of type struct:
type FuncParser struct {parser ParserFunc funcName string}
FuncParser implements the Parser interface :
func (f *FuncParser) Parser(contents []byte, url string) ParserResult {return f.Parser(contents, url)}func (f *FuncParser) Serialize() (funcName string, args interface{}) {return f.funcName, nil}
Aside from the overall complexity of the crawler code, simplify the code to the following:
type ParserFunc func(url string) stringtype FuncParser struct {parser ParserFunc}func (f *FuncParser) Parser(url string) string {return f.Parser(url)}func main() {funcParse := FuncParser{ func(url string) string {return url },} func Parse.Parser("http://www.zhenai.com/zhenghun")}
The same error will be reported after running the code:
runtime: goroutine stack exceeds 1000000000-byte limit
fatal error: stack overflow
runtime stack:
runtime.throw(0x467297, 0xe)
D:/Program Files/Go/go103/src/runtime/ panic.go:616 +0x88
runtime.newstack()
D:/Program Files/Go/go103/src/runtime/stack.go:1054 +0x72d
runtime.morestack()
D:/Program Files/Go/go103/src/runtime/asm_amd64.s:480 +0x91
This example is very obvious. A recursive call is formed in FuncParser’s Parser. Self),
recursively calling itself causes stack overflow, resulting in an error. It should be changed to this: (lowercase parser)
< /p>
In fact, Recursive Call has been prompted in goland
If you accidentally write this code, look at the following code:
package mainimport ("fmt")type Str stringfunc ( s Str) String() string {return fmt.Sprintf("Str: %s", s)}func main() {var s Str = "hi" fmt.Println(s)}
The same Error:
You are implementing Str.String in terms of itself. return fmt.Sprintf(“Str: %s”, s) will call s.String(), resulting in infinite recursion. Convert s to string first.
This is working as intended, you are using the %s verb to call Str’s String method, which uses fmt.Sprint to call Str’s String method, and so on.
As follows:
In fact, there will be warnings about this issue in goland:
It seems that when you write code, you should pay attention to warnings.
For the project code, please see: https://github.com/ll837448792/crawler
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