Question

I’ve got a google appengine app which runs some code on dynamic backend defined as follows:

backends:
- name: downloadfilesbackend
  class: B1
  instances: 1
  options: dynamic

I’ve recently made some changes to my code and added a second backend. I’ve moved some tasks from the front end to the new backend and they work fine. However I want to move the tasks that originally ran on downloadfilesbackend to the new backend (to save on instance hours). I am doing this simply by changing the name of the target to the new backend i.e.

taskqueue.add(queue_name = "organise-files",
        url=queue_organise_files,
        target='organise-files-backend')

However, despite giving the new backend name as the target the tasks are still being run by the old backend. Any idea why this is happening or how I can fix it?

EDIT:
The old backend is running new tasks – I’ve checked this.

I’ve also been through all of my code to check to see if anything is calling the old backend and nothing is. There are only two methods which added tasks to the old backend, and both of these methods have been changed as detailed above.

I stopped the old backend for a few hours, to see whether this would change anything, but all that happened was that the tasks got jammed until I restarted the backend. The new backend is running other tasks fine, so it’s definitely been updated correctly…

Answer 1

It’s taken a while but I’ve finally discovered that it is not enough to just change the code and upload it using the SDK. If the code running on the backend or sending tasks to the backend handler is changed then you must run

appcfg backends <dir> update [backend]

documentation for this command is here. There isn’t any documentation I’ve seen that says this – it was related to another related error I was experiencing that prompted this as an avenue. Just thought I’d let people know who may be having a similar problem