Google App Engine deferred.defer task not getting executed - python-2.7

Question

I have a Google App Engine Standard Environment application that has been working fine for a year or more, that, quite suddenly, refuses to enqueue new deferred tasks using deferred.defer.
Here's the Python 2.7 code that is making the deferred call:
# Find any inventory items that reference the product, and change them too.
# because this could take some time, we'll do it as a deferred task, and only
# if needed.
if upd:
updater = deferredtasks.InvUpdate()
deferred.defer(updater.run, product_key)
My app.yaml file has the necessary bits to support deferred.defer:
- url: /_ah/queue/deferred
script: google.appengine.ext.deferred.deferred.application
login: admin
builtins:
- deferred: on
And my deferred task has logging in it so I should see it running when it does:
#-------------------------------------------------------------------------------
# DEFERRED routine that updates the inventory items for a particular product. Should be callecd
# when ANY changes are made to the product, because it should trigger a re-download of the
# inventory record for that product to the iPad.
#-------------------------------------------------------------------------------
class InvUpdate(object):
def __init__(self):
self.to_put = []
self.product_key = None
self.updcount = 0
def run(self, product_key, batch_size=100):
updproduct = product_key.get()
if not updproduct:
logging.error("DEFERRED ERROR: Product key passed in does not exist")
return
logging.info(u"DEFERRED BEGIN: beginning inventory update for: {}".format(updproduct.name))
self.product_key = product_key
self._continue(None, batch_size)
...
When I run this in the development environment on my development box, everything works fine. Once I deploy it to the App Engine server, the inventory updates never get done (i.e. the deferred task is not executed), and there are no errors (and no other logging from the deferred task in fact) in the log files on the server. I know that with the sudden move to get everybody on Python 3 as quickly as possible, the deferred.defer library has been marked as not recommended because it only works with the 2.7 Python environment, and I planned on moving to task queues for this, but I wasn't expecting deferred.defer to suddenly stop working in the existing python environment.
Any insight would be greatly appreciated!

Answer 1

I'm pretty sure you cant pass the method of an instance to appengine taskqueue, because that instance will not get exist when your task runs since it will be running in a different process. I actually dont understand how your task ever worked when running remotely in the first place (and running locally is not an accurate representation of how things will run remotely)
Try changing your code to this:
if upd:
deferred.defer(deferredtasks.InvUpdate.run_cls, product_key)
and then InvUpdate is the same but has a new function run_cls:
class InvUpdate(object):
#classmethod
def run_cls(cls, product_key):
cls().run(product_key)
And I'm still on the process of migrating to cloud tasks and my deferred tasks still work