如何正确配置Google App Engine Java应用程序？

Question

I am following the Google's Tutorial on creating your first GAE Java Project. When I create it exactly the same as theirs I get lots of errors. I believe that it is caused wrong application configuration. Below are my configuration files:

appengine-web.xml

<?xml version="1.0" encoding="utf-8"?>
<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
  <application>my_app_id</application>
  <version>1</version>
</appengine-web-app>

appengine-web.xml

<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="2.5">
    <servlet>
        <servlet-name>guestbook</servlet-name>
        <servlet-class>guestbook.GuestbookServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>guestbook</servlet-name>
        <url-pattern>/guestbook</url-pattern>
    </servlet-mapping>
    <welcome-file-list>
        <welcome-file>guestbook.jsp</welcome-file>
    </welcome-file-list>
</web-app>

Answer 1

What you need is probably is to beat the evil zombie wizards by enable Using Concurrent Requests

By default, App Engine sends requests serially to a given web server. You can configure App Engine to send multiple requests in parallel by adding the element to appengine-web.xml :

In your appengine-web.xml :

<threadsafe>true</threadsafe>

Answer 2

Just for better readability, you might want to configure GAE/J using app.yaml https://cloud.google.com/appengine/docs/flexible/java/configuring-your-app-with-app-yaml

GAE will use the app.yaml to generate both web.xml and appengine-web.xml. I also just find the app.yaml syntax much easier to read.