appengine hot deploy on mac

1. Install JRebel
2. In Eclipse go to Help -> Install New Software... and download JRebel plugin http://www.zeroturnaround.com/update-site
3. Specified jrebel.jar jar in Eclipse / JRebel.
4. Modify dev_appserver.sh and let it something like this:

java -ea -cp "$JAR_FILE" \
com.google.appengine.tools.KickStart
--jvm_flag=-javaagent:$REBEL_HOME/jrebel.jar --jvm_flag=-noverify \
com.google.appengine.tools.development.DevAppServerMain $*

5. Add to the Run Configuration this VM Argument

-javaagent:/path/to/jrebel/jrebel.jar -noverify

6. Now it must works!

Taken from this steps for Windows http://androidisland.blogspot.com/2010/09/appengine-jrebel-and-eclipse-getting.html