App Engine：Go - Latency

Question

您好我制作了一个简单的照片博客应用程序，当我将其部署到App Engine时，它在主页上更新图片时出现问题。当我上传图片并返回主页时，需要几次刷新才能显示图像。 https://hello-world-170523.appspot.com/。

登录信息： 电子邮件：test@example.com
密码：测试

这是源代码：

package main

import (
    "fmt"
    "html/template"
    "io"
    "net/http"
    "os"
    "path/filepath"
    "strings"

    "google.golang.org/appengine"

    "github.com/gorilla/sessions"
)

type IndexPage struct {
    Photos  []string
    LogedIn bool
}

type LoginPage struct {
    Body      string
    FirstName string
    LastName  string
    Email     string
    Error     string
}
type UploadPage struct {
    Error string
    Msg   string
}

func getPhotos() []string {
    photos := make([]string, 0)
    filepath.Walk("assets/img", func(path string, fi os.FileInfo, err error) error {
        if fi.IsDir() {
            return nil
        }
        path = strings.Replace(path, "\\", "/", -1)
        photos = append(photos, path)
        return nil
    })
    return photos
}

var store = sessions.NewCookieStore([]byte("HelloWorld"))

func loginPage(res http.ResponseWriter, req *http.Request) {
    loginError := ""
    session, _ := store.Get(req, "session")
    str, _ := session.Values["logged-in"].(string)
    if str == "YES" {
        http.Redirect(res, req, "/admin", 302)
        return
    }
    if req.Method == "POST" {
        email := req.FormValue("email")
        password := req.FormValue("password")
        if email == "test@example.com" && password == "test" {
            session.Values["logged-in"] = "YES"
            session.Save(req, res)
            http.Redirect(res, req, "/admin", 302)
            return
        } else {
            loginError = "Invalid Credential. Please Resubmit"
        }
    }
    tpl, err := template.ParseFiles("assets/tpl/login.gohtml", "assets/tpl/header.gohtml")
    if err != nil {
        http.Error(res, err.Error(), 500)
        return
    }
    err = tpl.Execute(res, LoginPage{
        Error: loginError,
    })
}

func admin(res http.ResponseWriter, req *http.Request) {
    uploadError := ""
    successMsg := ""
    session, _ := store.Get(req, "session")
    str, _ := session.Values["logged-in"].(string)
    if str != "YES" {
        http.Redirect(res, req, "/login", 302)
        return
    }
    if req.Method == "POST" {
        // <input type="file" name="file">
        src, hdr, err := req.FormFile("file")
        if err != nil {
            http.Error(res, "Invalid File.", 500)
            return
        }

        defer src.Close()
        // create a new file
        // make sure you have a "tmp" directory in your web root
        dst, err := os.Create("assets/img/" + hdr.Filename)
        if err != nil {
            http.Error(res, err.Error(), 500)
            return
        }

        defer dst.Close()

        // copy the uploaded file into the new file
        io.Copy(dst, src)
    }
    tpl, err := template.ParseFiles("assets/tpl/admin.gohtml", "assets/tpl/header.gohtml")
    if err != nil {
        http.Error(res, err.Error(), 500)
        return
    }
    err = tpl.Execute(res, UploadPage{
        Error: uploadError,
        Msg:   successMsg,
    })
    if err != nil {
        http.Error(res, err.Error(), 500)
    }
}

func index(res http.ResponseWriter, req *http.Request) {
    session, _ := store.Get(req, "session")
    str, _ := session.Values["logged-in"].(string)
    logged := false
    if str == "YES" {
        logged = true
    }

    tpl, err := template.ParseFiles("assets/tpl/index.gohtml", "assets/tpl/header.gohtml")
    if err != nil {
        fmt.Println(err)
        http.Error(res, err.Error(), 500)
        return
    }
    err = tpl.Execute(res, IndexPage{
        Photos:  getPhotos(),
        LogedIn: logged,
    })
    if err != nil {
        fmt.Println(err)
        http.Error(res, err.Error(), 500)
    }
}

func logout(res http.ResponseWriter, req *http.Request) {
    session, _ := store.Get(req, "session")
    str, _ := session.Values["logged-in"].(string)
    if str == "YES" {
        delete(session.Values, "logged-in")
        session.Save(req, res)
        http.Redirect(res, req, "/", 302)
    } else {
        http.Redirect(res, req, "/login", 302)
    }
}

func deletePic(res http.ResponseWriter, req *http.Request) {
    session, _ := store.Get(req, "session")
    str, _ := session.Values["logged-in"].(string)
    if str != "YES" {
        http.Redirect(res, req, "/", 302)
        return
    }

    if req.Method == "POST" {
        imgName := req.FormValue("imgName")
        err := os.Remove(imgName)
        if err != nil {
            http.Error(res, err.Error(), 500)
        }
    }

    tpl, err := template.ParseFiles("assets/tpl/delete.gohtml", "assets/tpl/header.gohtml")
    if err != nil {
        http.Error(res, err.Error(), 500)
    }
    err = tpl.Execute(res, IndexPage{
        Photos: getPhotos(),
    })
    if err != nil {
        http.Error(res, err.Error(), 500)
    }
}

func main() {
    http.HandleFunc("/delete", deletePic)
    http.Handle("/assets/", http.StripPrefix("/assets", http.FileServer(http.Dir("./assets"))))
    http.HandleFunc("/", index)
    http.HandleFunc("/admin", admin)
    http.HandleFunc("/login", loginPage)
    http.HandleFunc("/logout", logout)
    appengine.Main()
}

我的app.yaml：

runtime: go
env: flex