运行此代码时,我必须等待10秒才能打印s.Locations,而要等待60+秒才能打印n.Titles。是什么原因造成的?
有关如何解决此问题的提示将很有帮助,即查看完成某些代码行需要多长时间。新手入门,所以不确定如何精确执行此操作。
我已确保关闭连接。由于我计算机上的所有其他内容都非常快,因此我认为通过http.Get访问互联网应该不会很慢。
package main
import (
"encoding/xml"
"fmt"
"io/ioutil"
"net/http"
"strings"
)
// SitemapIndex is the root xml
type SitemapIndex struct {
Locations []string `xml:"sitemap>loc"`
}
// News is the individual categories
type News struct {
Titles []string `xml:"url>news>title"`
Keywords []string `xml:"url>news>keywords"`
Locations []string `xml:"url>loc"`
}
// NewsMap is the
type NewsMap struct {
Keywords string
Location string
}
func main() {
var s SitemapIndex
var n News
// np := make(map[string]NewsMap)
resp, _ := http.Get("https://www.washingtonpost.com/news-sitemaps/index.xml")
bytes, _ := ioutil.ReadAll(resp.Body)
xml.Unmarshal(bytes, &s)
resp.Body.Close()
for i := range s.Locations {
s.Locations[i] = strings.TrimSpace(s.Locations[i])
}
fmt.Println(s.Locations) // slice of data
for _, Location := range s.Locations {
resp, _ := http.Get(Location)
bytes, _ := ioutil.ReadAll(resp.Body)
xml.Unmarshal(bytes, &n)
resp.Body.Close()
}
fmt.Println(n.Titles)
}
我得到了输出,但我必须等待10秒才能找到s.Locations,而要等待60+秒才能看到n.Titles
最佳答案
从简单的事情开始,一次测量一件事,一次科学实验。
使用curl
衡量基本响应时间。
$ curl https://www.google.com/robots.txt -o /dev/null
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 7246 0 7246 0 0 94103 0 --:--:-- --:--:-- --:--:-- 94103
$ curl https://www.nytimes.com/robots.txt -o /dev/null
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 934 100 934 0 0 61 0 0:00:15 0:00:15 --:--:-- 230
$ curl https://www.washingtonpost.com/robots.txt -o /dev/null
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 3360 100 3360 0 0 133 0 0:00:25 0:00:25 --:--:-- 869
$
Google刻不容缓。纽约时报有15秒的延迟。 《华盛顿邮报》有25秒的延迟。
在Go中,确认《华盛顿邮报》有25秒的延迟。
$ go run wapo.go
25.174366651s
$ cat wapo.go
package main
import (
"fmt"
"io/ioutil"
"net/http"
"os"
"time"
)
func main() {
start := time.Now()
resp, err := http.Get("https://www.washingtonpost.com/news-sitemaps/index.xml")
if err != nil {
fmt.Fprintln(os.Stderr, err)
return
}
_, err = ioutil.ReadAll(resp.Body)
if err != nil {
fmt.Fprintln(os.Stderr, err)
return
}
resp.Body.Close()
fmt.Fprintln(os.Stderr, time.Since(start))
}
$
接下来,尝试使用其他计算机上的其他ISP。
$ curl https://www.google.com/robots.txt -o /dev/null
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 7246 0 7246 0 0 27343 0 --:--:-- --:--:-- --:--:-- 27343
$ curl https://www.nytimes.com/robots.txt -o /dev/null
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 934 100 934 0 0 2017 0 --:--:-- --:--:-- --:--:-- 2017
$ curl https://www.washingtonpost.com/robots.txt -o /dev/null
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 3360 100 3360 0 0 356 0 0:00:09 0:00:09 --:--:-- 840
$ curl https://www.washingtonpost.com/news-sitemaps/index.xml -o /dev/null
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 1101 100 1101 0 0 104 0 0:00:10 0:00:10 --:--:-- 266
$
$ go run wapo.go
8.378458882s
$
Google刻不容缓。纽约时报有一点延迟。 《华盛顿邮报》有9秒的延迟。
Go代码和编译器相同:
$ go version
go version devel +a25c2878c7 Sat Jul 27 23:29:18 2019 +0000 linux/amd64
$ cat wapo.go
package main
import (
"fmt"
"net/http"
"os"
"time"
)
func main() {
start := time.Now()
resp, err := http.Get("https://www.washingtonpost.com/news-sitemaps/index.xml")
if err != nil {
fmt.Fprintln(os.Stderr, err)
return
}
resp.Body.Close()
fmt.Fprintln(os.Stderr, time.Since(start))
}
$
因此,重点关注网络和站点因素。