Yeah sorry - I'm using pure java (servlets/jsps) on HR datastore, the user facing app is on
http://www.librarist.com/ (which is spring mvc deployed on appfog talking with app engine backend). All day today I see a lot of app instance to be started and killed within few seconds, none of them have more than 200 requests processed - usually my dynamic instances serve ~50k requests in their live.
And the best part is that google is going to charge me extra for the CPU (I know it's few cents but what an irony) which they waste on spining/killing those instances while they just could run one dynamic forever which is usually able to server whatever my app needs.