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Fix: Make URL cache clearing thread-safe in _django_set_urlconf #1233

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Fix: Make URL cache clearing thread-safe in _django_set_urlconf #1233

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049534b
Fix: Make URL cache clearing thread-safe in _django_set_urlconf
pankaj-bind Aug 13, 2025
c746a9b
fix linting error
pankaj-bind Aug 13, 2025
c2b5438
fix linting error
pankaj-bind Aug 13, 2025
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23 changes: 13 additions & 10 deletions pytest_django/plugin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
import os
import pathlib
import sys
import threading
import types
from collections.abc import Generator
from contextlib import AbstractContextManager
Expand Down Expand Up @@ -64,6 +65,8 @@

# ############### pytest hooks ################

urlconf_lock = threading.Lock()


@pytest.hookimpl()
def pytest_addoption(parser: pytest.Parser) -> None:
Expand Down Expand Up @@ -646,20 +649,20 @@ def _django_set_urlconf(request: pytest.FixtureRequest) -> Generator[None, None,
import django.conf
from django.urls import clear_url_caches, set_urlconf

urls = validate_urls(marker)
original_urlconf = django.conf.settings.ROOT_URLCONF
django.conf.settings.ROOT_URLCONF = urls
clear_url_caches()
set_urlconf(None)
with urlconf_lock:
urls = validate_urls(marker)
original_urlconf = django.conf.settings.ROOT_URLCONF
django.conf.settings.ROOT_URLCONF = urls
clear_url_caches()
set_urlconf(None)

yield

if marker:
django.conf.settings.ROOT_URLCONF = original_urlconf
# Copy the pattern from
# https://github.com/django/django/blob/main/django/test/signals.py#L152
clear_url_caches()
set_urlconf(None)
with urlconf_lock:
django.conf.settings.ROOT_URLCONF = original_urlconf
clear_url_caches()
set_urlconf(None)


@pytest.fixture(autouse=True, scope="session")
Expand Down
44 changes: 44 additions & 0 deletions tests/test_urls.py
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Original file line number Diff line number Diff line change
Expand Up @@ -107,3 +107,47 @@ def test_something_else():

result = django_pytester.runpytest_subprocess()
assert result.ret == 0


@pytest.mark.django_project(
extra_settings="""
ROOT_URLCONF = "empty"
"""
)
def test_urls_concurrent(django_pytester: DjangoPytester) -> None:
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@kingbuzzman kingbuzzman Aug 13, 2025

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I copied this test over to my main branch, and ran this on py3.13

count=0
while true; do
    count=$((count + 1))
    if ! pytest tests/test_urls.py -vv > /dev/null 2>&1; then
        echo "Test failed on iteration $count"
        break
    fi
    printf "."
done

it has not failed -- keeps going, after 100+ iterations (keep in mind, i only copied the test, not the "fix")

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@kingbuzzman kingbuzzman Aug 13, 2025

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PS. I also ran this with pytest -n auto (same loop as above) -- no difference, i dont see the race condition

"Test that the URL cache clearing is thread-safe with pytest-xdist."
pytest.importorskip("xdist")

django_pytester.makepyfile(
empty="urlpatterns = []",
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@kingbuzzman kingbuzzman Aug 13, 2025

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Not used

Suggested change
empty="urlpatterns = []",

urls1="""
from django.urls import path
urlpatterns = [path('url1/', lambda r: None, name='url1')]
""",
urls2="""
from django.urls import path
urlpatterns = [path('url2/', lambda r: None, name='url2')]
""",
)

django_pytester.create_test_module(
"""
import pytest
from django.urls import reverse, NoReverseMatch

@pytest.mark.urls('urls1')
def test_urls1():
reverse('url1')
with pytest.raises(NoReverseMatch):
reverse('url2')

@pytest.mark.urls('urls2')
def test_urls2():
reverse('url2')
with pytest.raises(NoReverseMatch):
reverse('url1')
"""
)

result = django_pytester.runpytest_subprocess("-n", "2")
assert result.ret == 0
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