[FIXED] django how can I use multiprocessing in a management command

Issue

how can I use multiprocessing in a django management command? I can't figure out how to start the process inside of my websites django context

management command

users = users.objects.filter(is_active=True)

with ProcessPoolExecutor(max_workers=5) as executor:
   processes = []
   for user in users:
       p = executor.submit(complex_user_calculation,user)
       processes.append(p)

   for f in concurrent.futures.as_completed(processes):
       result = f.result()
       if result:
           print(result)

when I run this management command I get this error

    raise AppRegistryNotReady("Apps aren't loaded yet.")
django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet.
...
  File "C:\Users\user\AppData\Local\Programs\Python\Python310\lib\concurrent\futures\_base.py", line 390, in __get_result
    raise self._exception
concurrent.futures.process.BrokenProcessPool: A process in the process pool was terminated abruptly while the future was running or pending.

Solution

You need to initialise your Django application in each subprocess to ensure your apps, models, etc are all loaded. Pass django.setup as your pool initialiser

with ProcessPoolExecutor(max_workers=5, initializer=django.setup) as executor:
    ...

Answered By - Iain Shelvington