Avoid loading all celery beat entities on create/update django admin forms

[matthieudesprez]

Summary:

• Celery Version: 5.0.5
• Celery-Beat Version: 2.2.0

Exact steps to reproduce the issue:

1. create 1M clocked schedules
2. try to reach /admin/django_celery_beat/periodictask/add/
3. 💥

Detailed information

Just run into this right now, we have a process that auto scheduled some tasks, and over the months it created more than a million clocked schedules. celery beat admin forms seem to try loading the whole list so it takes a long time to render and eventually times out on most server configurations.

[auvipy]

can you check the resource usage? if increasing server resources solve the issue to some extent?

[matthieudesprez]

I'm pretty sure it will, but then having more clocked schedules might definitely causes the same issue because they're all loaded to appear in the dropdown of the periodic task form.