Better deferred handler names for debugging and appstats

app,yaml

- url: /_ah/queue/deferred/.*
  script: google.appengine.ext.deferred.application

deferred.py

from google.appengine.ext import deferred


def do_defer(obj, *args, **kwargs):
    _DEFAULT_URL = "/_ah/queue/deferred"

    tag = kwargs.pop("_tag") if kwargs.get('_tag') else None

    if not tag and kwargs.get('_queue'):
        tag = kwargs.get('_queue')

    kwargs['_url'] = '%s/%s' % (_DEFAULT_URL, tag or 'notag')

    deferred.defer(obj, *args, **kwargs)

When using deferred in App Engine you have the problem that all diagnostic is on the same handler although you might be using it for different functionality.

This means in the the event log, appstat and requests diagnostics (on the main dashboard page) you will see everything under the /_ah/queue/deferred entry.

In order to get better context to which each defer belongs use do_defer instead of deferred.defer and add the above yaml code to your app.yaml.

The code will add the queue name to the handler path (e.g. /_ah/queue/deferred/my-queue) or you can pass the _tag property (do_defer(my_method, _tag='method-tag')) to control the path text.