Tukukkk

I have a Django app, with a setting (in my settings.py file) that's populated dynamically in my App Config's ready() function. Ie in settings.py I have:

POPULATE_THIS = None

and then in apps.py in ready I have:

def ready(self):

    if POPULATE_THIS is None:

        POPULATE_THIS = ... some code which instantiates an object I need that's effectively a singleton ...

This seems to work ok. But I'm now at the point where rather than just running the dev server locally (ie python manage.py runserver), I'm now running the Django app through uwsgi (proxied behind nginx), and uwsgi is configured to run 10 worker processes (ie my uwsgi ini file has processes = 10 and threads = 1).

I'm seeing evidence that even though there are 10 uwsgi processes , ready() is still called exactly once on app startup and the value of POPULATE_THIS is the same across all workers (doing a str on it is giving the same memory address).

My question: How is that value shared across the uwsgi processes, as I thought separate processes are distinct and do not share any memory? And am I correct in assuming that ready() is going to be called once per app startup (ie when uwsgi itself spins up), and not once per uwsgi worker process startup?

This answer (Multiple server processes using nginx and uWSGI) on a different question seems to indicate that some data is shared across workers, but I can't seem to find any official docs that indicate what exactly is shared and how, specifically with respect to Django settings, so some explanation/details would be much appreciated.

Exactly.

It seems that uwsgi only spam processes of the django application itself, therefore all the functions ready will be called only once, during the first run.