I'm building a Django app to listen to a Pubnub feed and store the messages in a database. I create a pubnub listener in my app's apps.py's AppConfig's ready() method.

Upon launching my app on Heroku, I get the really unhelpful error

2017-04-26T02:17:50.038060+00:00 heroku[web.1]: Error R12 (Exit timeout) -> At least one process failed to exit within 30 seconds of SIGTERM
2017-04-26T02:17:50.038060+00:00 heroku[web.1]: Stopping remaining processes with SIGKILL
2017-04-26T02:17:50.134619+00:00 heroku[web.1]: Process exited with status 137

I suspect django wants to clean up the AppConfig process and is getting upset that there is a pubnub object hanging around in there. Is that the problem? How do I fix it?

I also see that (at least implicitly by example) Heroku recommends using the twisted interface. Is it bad that I'm not?

Here's the relevant code:

I created a mypubnub.py based on Pubnub's hello world example:

from pubnub.pubnub import PubNub
from pubnub.pnconfiguration import PNConfiguration
from pubnub.callbacks import SubscribeCallback


class MySubscribeCallback(SubscribeCallback):
    def presence(self, pubnub, presence):
        pass

    def status(self, pubnub, status):
        pass

    def message(self, pubnub, message):
        pass  # I'll actually do the storage here later


def create_pubnub():
    pnconf = PNConfiguration()
    pnconf.subscribe_key = 'sub-c-blargyblargblarg'
    pnconf.publish_key = 'pub-c-blargyblargblarg'
    pubnub = PubNub(pnconf)

    pubnub.add_listener(MySubscribeCallback())
    pubnub.subscribe().channels('achannel').execute()

    return pubnub

I instantiate that pubnub stuff in apps.pyfrom django.apps import AppConfig

from .mypubnub import create_pubnub

class MyAppConfig(AppConfig):
    name = 'myapp'

    def ready(self):
        pn = create_pubnub()