SCRIPT_NAME / FORCE_SCRIPT_NAME ignored when running reverse() on non-main thread

[Pēteris Caune]

I've configured my Django project to run on a subpath (under example.org/some_prefix instead of example.org).

The project has a management command which generates URLs using django.urls.reverse().

Since the management command cannot read SCRIPT_NAME from WSGI parameters, the project has FORCE_SCRIPT_NAME = "/some_prefix" in settings.py.

The management command generates URLs that include the prefix as expected if the code runs on main thread. But if the management command spawns a thread, the code running on thread generates URLs without the prefix.

I'm not sure but I think this is related to hc.urls.base._prefix being a Local object. I'm guessing it, as the name suggests, does not share data between threads. Even though set_script_prefix is called on main thread, the other threads do not see it.

A simple workaround is for the user to call set_script_prefix by themselves:

from django.conf import settings
from django.urls import set_script_prefix

def this_will_be_run_on_thread():
    if settings.FORCE_SCRIPT_NAME:
        set_script_prefix(settings.FORCE_SCRIPT_NAME)
    # do work here    

But perhaps there's something Django could do here as well:

• perhaps, change django.urls implementation so that threads do share the script prefix storage?
• if there are disadvantages to that, mention this gotcha in the documentation

I'm happy to provide a dummy project demonstrating the issue if that would be helpful.