有人可以解释为什么以下gocode与goapp服务失败 [英] Could someone explain why the following gocode fails with goapp serve

问题描述

  package helloworld 
 
导入（
fmt
net / http
 
appengine 
appengine / user
）
 
 func init（）{
 fmt.Print（hello）
 http.HandleFunc（/ ，处理程序）
} 
 
 func处理程序（w http.ResponseWriter，r * http.Request）{
c：= appengine.NewContext（r）
u：= user.Current（c）
 if u == nil {
 url，err：= user.LoginURL（c，r.URL.String（））
 if err！= nil {
 http.Error（w，err.Error（），http.StatusInternalServerError）
 return 
} 
 w.Header（）。Set（Location，url）
 w.WriteHeader（http.StatusFound）
 return 
} 
 fmt.Fprintf（w，Hello，％v！，u）
} 
  code> 

在 goapp serve 输出中输出以下错误

 （saucy）adam @ localhost：〜/ projects / ringed-land-605 / default $ goapp serve -host 0.0.0.0。 
 INFO 2014-06-08 23：57：47,862 devappserver2.py:716]跳过SDK更新检查。 
 INFO 2014-06-08 23：57：47,877 api_server.py:171]启动API服务器：http：// localhost：48026 
 INFO 2014-06-08 23：57：47,923调度程序。 py：182]启动模块default运行在：http：//0.0.0.0:8080 
 INFO 2014-06-08 23:57:47,925 admin_server.py:117]启动管理服务器：http：/ / localhost：8000 
 ERROR 2014-06-08 23：57：48,759 http_runtime.py:262]错误的运行时进程端口['hello46591 \ n'] 
  

删除 fmt.Print（）可以解决问题。我的问题是为什么会发生这种情况？

解决方案

当启动运行时进程时， Go Development Server （位于App Engine Go SDK中）正在读取您的helloworld <$ c $中的单行响应c> init 。

这会修改 _start_process_flavor 标志> http_runtime.py ;因此，HTTP运行时会尝试读取线路以侦听哪个端口。

读取开始时预计的单行响应处理文件。 [...] START_PROCESS_FILE flavor为运行时实例使用文件来报告它正在监听的端口。例如， hello 不是有效的端口。

---

<请尝试使用Go的 log 软件包：

  log.Print（hello）
  

package helloworld

import (
  "fmt"
  "net/http"

  "appengine"
  "appengine/user"
)

func init() {
  fmt.Print("hello")
  http.HandleFunc("/", handler)
}

func handler(w http.ResponseWriter, r *http.Request) {
  c := appengine.NewContext(r)
  u := user.Current(c)
  if u == nil {
    url, err := user.LoginURL(c, r.URL.String())
    if err != nil {
      http.Error(w, err.Error(), http.StatusInternalServerError)
      return
    }
    w.Header().Set("Location", url)
    w.WriteHeader(http.StatusFound)
    return
  }
  fmt.Fprintf(w, "Hello, %v!", u)
}

Throw the following error in goapp serve output

(saucy)adam@localhost:~/projects/ringed-land-605/default$ goapp serve -host 0.0.0.0 .
INFO     2014-06-08 23:57:47,862 devappserver2.py:716] Skipping SDK update check.
INFO     2014-06-08 23:57:47,877 api_server.py:171] Starting API server at: http://localhost:48026
INFO     2014-06-08 23:57:47,923 dispatcher.py:182] Starting module "default" running at: http://0.0.0.0:8080
INFO     2014-06-08 23:57:47,925 admin_server.py:117] Starting admin server at: http://localhost:8000
ERROR    2014-06-08 23:57:48,759 http_runtime.py:262] bad runtime process port ['hello46591\n']

Removing the fmt.Print() fixes the issue. My question is why does that happen?

解决方案

When starting the runtime process, the Go Development Server (in the App Engine Go SDK) is reading the single line response found in your helloworld's init.

This modifies the _start_process_flavor flag in http_runtime.py; consequently, the HTTP runtime attempts to read the line for direction on which port to listen to.

Read the single line response expected in the start process file. [...] The START_PROCESS_FILE flavor uses a file for the runtime instance to report back the port it is listening on.

In this case, hello isn't a valid port to listen on.

---

Try using Go's log package instead:

log.Print("hello")

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