Google App Engine App with JPA deployment hangs

I have a java GAE web app with datanucleus as the JPA provider. When 开发者_开发知识库deploying locally on my machine - the deployment hangs (takes minutes). Looking at the task manager I have a javac process running. Any idea what is going wrong?

Agreed. Its the problem with GAE as it takes a 6permutation Compilation only after which the application would be deployed and shown on the browser. I feel its the problem only with GAE and not JPA. I have developed a similar app and if you feel its because of JPA, you can check the corresponding database admin to see how many threads are being opened for the user. If you seem to find some aren't Garbage collected, check your code. Else you can use ConnectionPooling mechanism (to speedup db retrieval using ORM).....

The answer depends on several parameters

• How you deploy, are you using eclipse or command line?
• GAE version (and GAE/GWT eclipse plugin version)
• Windows or Linux?

In any case, a Thread Dump can help seeing which non daemon threads are stuck.

For command line deployment in Windows - press CtrlBreak after it hangs to get the thread dump

In Eclipse, if there is a way to deploy in debug mode, look at the debug view stack for the same info
See this answer as well: How to Force Thread Dump in Eclipse?

This thing depend on which platform u r using

1. Windows
2. linux
3. mac os x

you can check what is going on by checksignal

sending a signal

Usage:

SendSignal <pid>
  <pid> - send ctrl-break to process <pid> (hex ok)
You can get the source via anonymous CVS at

cvs -d :pserver:anon@www.latenighthacking.com:/code-cvsroot co 2003/SendSignal

I have recently deployed my simple application in google app engine via eclipse. It failed to deploy couple of times. after sometime, It deploy successfully. I was able to access the application. if it hangs, stop the deployment process and redeply