Refs #24007 -- Removed an apps.populate() call in model unpickling that can cause deadlocks.

This commit is contained in:
Tim Graham 2016-01-26 07:03:54 -05:00
parent db9f21f0ad
commit 10a162809f
3 changed files with 11 additions and 49 deletions

View File

@ -1694,8 +1694,6 @@ def model_unpickle(model_id, attrs, factory):
Used to unpickle Model subclasses with deferred fields.
"""
if isinstance(model_id, tuple):
if not apps.ready:
apps.populate(settings.INSTALLED_APPS)
model = apps.get_model(*model_id)
else:
# Backwards compat - the model was cached directly in earlier versions.

View File

@ -461,6 +461,16 @@ Since the introduction of migrations for the contrib apps in Django 1.8, the
tables of these custom user test models were not created anymore making them
unusable in a testing context.
Apps registry is no longer auto-populated when unpickling models outside of Django
----------------------------------------------------------------------------------
The apps registry is no longer auto-populated when unpickling models. This was
added in Django 1.7.2 as an attempt to allow unpickling models outside of
Django, such as in an RQ worker, without calling ``django.setup()``, but it
creates the possibility of a deadlock. To adapt your code in the case of RQ,
you can `provide your own worker script <http://python-rq.org/docs/workers/>`_
that calls ``django.setup()``.
Miscellaneous
-------------

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@ -1,17 +1,9 @@
import datetime
import os
import pickle
import subprocess
import sys
from django.core.files.temp import NamedTemporaryFile
from django.db import DJANGO_VERSION_PICKLE_KEY, models
from django.test import TestCase, mock
from django.utils._os import npath, upath
from django.test import TestCase
from django.utils.version import get_version
from .models import Article
class ModelPickleTestCase(TestCase):
def test_missing_django_version_unpickling(self):
@ -51,41 +43,3 @@ class ModelPickleTestCase(TestCase):
msg = "Pickled model instance's Django version 1.0 does not match the current version %s." % get_version()
with self.assertRaisesMessage(RuntimeWarning, msg):
pickle.loads(pickle.dumps(p))
def test_unpickling_when_appregistrynotready(self):
"""
#24007 -- Verifies that a pickled model can be unpickled without having
to manually setup the apps registry beforehand.
"""
script_template = """#!/usr/bin/env python
import pickle
from django.conf import settings
data = %r
settings.configure(DEBUG=False, INSTALLED_APPS=['model_regress'], SECRET_KEY = "blah")
article = pickle.loads(data)
print(article.headline)"""
a = Article.objects.create(
headline="Some object",
pub_date=datetime.datetime.now(),
article_text="This is an article",
)
with NamedTemporaryFile(mode='w+', suffix=".py") as script:
script.write(script_template % pickle.dumps(a))
script.flush()
# A path to model_regress must be set in PYTHONPATH
model_regress_dir = os.path.dirname(upath(__file__))
model_regress_path = os.path.abspath(model_regress_dir)
tests_path = os.path.split(model_regress_path)[0]
pythonpath = os.environ.get('PYTHONPATH', '')
pythonpath = npath(os.pathsep.join([tests_path, pythonpath]))
with mock.patch.dict('os.environ', {'PYTHONPATH': pythonpath}):
try:
result = subprocess.check_output([sys.executable, script.name])
except subprocess.CalledProcessError:
self.fail("Unable to reload model pickled data")
self.assertEqual(result.strip().decode(), "Some object")