go | 易学教程

Performance problem with read and parse large XML files

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问题 I have a directory which contains several large XML files (total size is about 10 GB). Is there any way to iterate through the directory containing the XML files and read 50 byte by 50 byte and parse the XML files with high performance? func (mdc *Mdc) Loadxml(path string, wg sync.WaitGroup) { defer wg.Done() //var conf configuration file, err := os.Open(path) if err != nil { log.Fatal(err) } defer file.Close() scanner := bufio.NewScanner(file) buf := make([]byte, 1024*1024) scanner.Buffer

liunx 安装 confluent-kafka-go

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安装librdkafka git clone https://github.com/edenhill/librdkafka.git cd librdkafka ./configure --prefix /usr make sudo make install 下载源码 go get -u github.com/confluentinc/confluent-kafka-go/kafka 以上都githup给出的，需要执行以下命令，否则会异常 sudo ldconfig /tmp/go-build616273194/b001/exe/consumer: error while loading shared libraries: librdkafka.so.1: cannot open shared object file: No such file or directory 来源： oschina 链接： https://my.oschina.net/u/3247419/blog/2050756

Python 基础

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零基础学Python，本文是我个人的随心笔记，希望对你有益！注释：单行：#……　　多行：单引号（’’’）双引号（”””）基本数据类型：整数：int；浮点数：float（只有这两种）；str：字符串；bool：布尔类型；complete：复数；list:列表；tuple:元组；set:集合；dict:字典 1 >>> type(2 ) 2 < class ' int ' > 3 >>> type(1.1 ) 4 < class ' float ' > 5 >>> type(1+1.1 ) 6 < class ' float ' > 7 >>> type(2/2 ) 8 < class ' float ' > 9 >>> type(2//2 ) 10 < class ' float ' > 11 >>> 2//2 12 1 13 >>> 2/2 14 1.0 15 >>> 2*2 16 4 基本类型 type()用来获取该表达式的数据类型 //: 除并取整 / ：除之后商有一位小数 1 print ( " I " , end= " " ) 2 print ( " love " , end= '' ) 3 print ( " you ! " ) # I love you !（没有换行）进制转换 1 >>> 0b10 # 二进制 2 2 3 >>> 0o10 # 八进制

Go, encoding/xml: How can I marshal self-closing elements?

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问题 I'm writing XML from the following struct: type OrderLine struct { LineNumber string `xml:"LineNumber"` Product string `xml:"Product"` Ref string `xml:"Ref"` Quantity string `xml:"Quantity"` Price string `xml:"Price"` LineTotalGross string `xml:"LineTotalGross"` } If the Ref field is empty, I'd like the element to display, but be self-closing, i.e. <Ref /> and not : <Ref></Ref> AFAIK, these two are semantically equivalent, but I would prefer a self-closing tag, as it matches the output from

什么是IPFS?IPFS与区块链有什么关系

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1.什么是IPFS? 　　IPFS 是 Inter Planetary File System （星际文件系统）的缩写，是一个典型的点对点分布式文件系统，旨在用同一个文件系统连接所有的计算设备。这时候有些小伙伴可能会问，为什么要使用分布式文件系统，我将我的文件存储在本地笔记本上，或者上传到云端（典型的云端提供商有AWS S3, Azure Cloud 等等）保管就好了呀，可用性高而且一般不会丢。其实对区块链技术有一点了解的小伙伴不难想到，这种中心化的服务器模式，很容易造成单点故障（服务提供商中断服务或者以违反规定为由，移除/屏蔽你的文件）。此外，随着文件存储数量的增加，存储成本也将变得越来越昂贵。在这种背景下，IPFS应用而生。　　在 IPFS 的世界里，这些服务提供商将不再是中心化服务器，而是 P2P 网络里的计算机。与任何人都可以运行一个以太坊节点一样，任何人也都可以运行一个 IPFS 节点，并加入网络来形成全球的文件系统。文件可以在很多节点间复制，几乎不可能出现无法访问文件的情况（IPFS 没有单故障点，节点不需要相互信任）。附上两种文件系统的对比图。此外，IPFS也被称为颠覆HTTP协议的协议，目前已成为事实上的分布式HTTP协议的工业标准。之所以这么讲是因为，目前我们所使用的WEB网络（即日常浏览的各大网站：百度，github，淘宝等等

Is there a way to dynamically unmarshal json base on content? [duplicate]

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问题 This question already has answers here : How to parse JSON in golang without unmarshaling twice (3 answers) How to parse a complicated JSON with Go unmarshal? (3 answers) Decoding generic JSON objects to one of many formats (1 answer) How to partially parse JSON using Go? (3 answers) Closed 1 year ago . I have a json format that looks like this { "my_object_list": [ { "meta": {"version": 1}, "my_value": {// Some complex value } } { "meta": {"version": 2}, "my_value": {// Some complex value }

Returning a Mock from a package function

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问题 I'm fairly new to Go and I'm having some issues with writing tests, specifically mocking the response of a package function. I'm writing an wrapper lib for github.com/go-redis/redis . At the moment it only really has better errors for failures, but it will be expanded with statsd tracking further down the line, but I digress... I have the following go package that I have created package myredis import ( "time" "github.com/go-redis/redis" errors "github.com/pkg/errors" ) var newRedisClient =

strconv.Atoi in Go (Basic calculator)

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问题 I'm trying to make a basic adding calculator in Go (complete noob here), but every time I'm getting an output of 0. This is the code: package main import ( "fmt" "strconv" //"flag" "bufio" "os" ) func main(){ reader := bufio.NewReader(os.Stdin) fmt.Print("What's the first number you want to add?: ") firstnumber, _ := reader.ReadString('\n') fmt.Print("What's the second number you want to add?: ") secondnumber, _ := reader.ReadString('\n') ifirstnumber, _ := strconv.Atoi(firstnumber)

strconv.Atoi in Go (Basic calculator)

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Method does not change the value of object if the object is in a slice

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问题 Here is my program: package main import ( "fmt" ) type Number struct { val int } func (num * Number) Increment () { num.val += 1 } func (num Number) Value() int { return num.val } func main() { numbers := []Number { {val: 12}, {val: 7}, {val: 0}, } for _, each := range numbers { each.Increment() fmt.Println(each.Value()) } for _, each := range numbers { fmt.Println(each.Value()) } } Here is the output: 13 8 1 12 7 0 First question: why does the Increment() method not update the value in the