How do dynamic backends start in Google App Engine

Question

Can we start a dynamic backend programatically? mean while when a backend is starting how can i handle the request by falling back on the application(i mean app.appspot.com).

When i stop a backend manually in admin console, and send a request to it, its not starting "dynamically"

Answer 1

Dynamic backends come into existence when they receive a request, and are turned down when idle; they are ideal for work that is intermittent or driven by user activity.

Resident backends run continuously, allowing you to rely on the state of their memory over time and perform complex initialization.

http://code.google.com/appengine/docs/python/backends/overview.html

I recently started executing a long running task on a dynamic backend and noticed a dramatic increase in the performance of the frontends. I assume this was because the long running task was competing for resources with normal user requests.

Answer 2

Backends are documented quite thoroughly here. Backends have to be started and stopped with appcfg or the admin console, as documented here. A stopped backend will not handle requests - if you want this, you should probably be using the Task Queue instead.