Short answer - Do not do this if there’s any chance at all that the subprocess might need to continue past the point that the view returns the response. Use Celery or one of the similar background-processing task managers.
Note that even Django’s Tasks framework works under the principle of disconnecting the view from those tasks:
The actual execution must be handled by infrastructure outside Django, such as a separate process or service.
For more on this, see:
(There are a number of other topics here discussing this. Searching the forum for “background tasks” or “background processes” will give you a number of them.)