我试图了解如何在内存sqlite3中并行运行django测试。
我有具有这种结构的django应用程序：
gbook
order
...
tests
__init__.py
test_a1.py
test_b1.py
utils.py
test_a1.py和test_b1.py包含相同的代码：
import time
from order import models
from .utils import BackendTestCase
class ATestCase(BackendTestCase):
def test_a(self):
time.sleep(1)
a = models.City.objects.count()
self.assertEqual(a, a)
class BTestCase(BackendTestCase):
def test_b(self):
time.sleep(1)
a = models.City.objects.count()
self.assertEqual(a, a)
utils.py是：
from django.test import TestCase, Client
from order import models
from django.conf import settings
from order.utils import to_hash
class BackendTestCase(TestCase):
fixtures = ['City.json', 'Agency.json']
def setUp(self):
self.client = Client()
self.lang_codes = (i[0] for i in settings.LANGUAGES)
...
settings_test.py：
from .settings import *
DEBUG = False
TEMPLATE_DEBUG = False
STATICFILES_STORAGE = 'django.contrib.staticfiles.storage.StaticFilesStorage'
PASSWORD_HASHERS = ['django.contrib.auth.hashers.MD5PasswordHasher',] # faster
DATABASES['default'] = {
'ENGINE': 'django.db.backends.sqlite3',
}
当我在单个过程中运行测试时，一切顺利（大约4秒钟）：
python.exe manage.py test order --settings=gbook.settings_test
然后我尝试并行运行测试：
python.exe manage.py test order --settings=gbook.settings_test --parallel=2
我得到了此跟踪信息（控制台）：
Creating test database for alias 'default'...
Cloning test database for alias 'default'...
Cloning test database for alias 'default'...
System check identified no issues (0 silenced).
Process SpawnPoolWorker-2:
Process SpawnPoolWorker-1:
Traceback (most recent call last):
Traceback (most recent call last):
File "C:\python\Python36-32\lib\multiprocessing\process.py", line 258, in _bootstrap
self.run()
File "C:\python\Python36-32\lib\multiprocessing\process.py", line 258, in _bootstrap
self.run()
File "C:\python\Python36-32\lib\multiprocessing\process.py", line 93, in run
self._target(*self._args, **self._kwargs)
File "C:\python\Python36-32\lib\multiprocessing\process.py", line 93, in run
self._target(*self._args, **self._kwargs)
File "C:\python\Python36-32\lib\multiprocessing\pool.py", line 108, in worker
task = get()
File "C:\python\Python36-32\lib\multiprocessing\pool.py", line 108, in worker
task = get()
File "C:\python\Python36-32\lib\multiprocessing\queues.py", line 337, in get
return _ForkingPickler.loads(res)
File "C:\python\Python36-32\lib\multiprocessing\queues.py", line 337, in get
return _ForkingPickler.loads(res)
File "C:\kvk\develop\Python\gbook\order\tests\test_a1.py", line 2, in <module>
from order import models
File "C:\kvk\develop\Python\gbook\order\tests\test_a1.py", line 2, in <module>
from order import models
File "C:\kvk\develop\Python\gbook\order\models.py", line 79, in <module>
class Agency(models.Model):
File "C:\kvk\develop\Python\gbook\order\models.py", line 79, in <module>
class Agency(models.Model):
File "C:\python\venv\gbook\lib\site-packages\django\db\models\base.py", line 110, in __new__
app_config = apps.get_containing_app_config(module)
File "C:\python\venv\gbook\lib\site-packages\django\db\models\base.py", line 110, in __new__
app_config = apps.get_containing_app_config(module)
File "C:\python\venv\gbook\lib\site-packages\django\apps\registry.py", line 247, in get_containing_app_config
self.check_apps_ready()
File "C:\python\venv\gbook\lib\site-packages\django\apps\registry.py", line 247, in get_containing_app_config
self.check_apps_ready()
File "C:\python\venv\gbook\lib\site-packages\django\apps\registry.py", line 125, in check_apps_ready
raise AppRegistryNotReady("Apps aren't loaded yet.")
File "C:\python\venv\gbook\lib\site-packages\django\apps\registry.py", line 125, in check_apps_ready
raise AppRegistryNotReady("Apps aren't loaded yet.")
django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet.
django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet.
与Pycharm跟踪不同：
...
Traceback (most recent call last):
File "C:\python\Python36-32\lib\unittest\suite.py", line 163, in _handleClassSetUp
setUpClass()
File "C:\python\venv\gbook\lib\site-packages\django\test\testcases.py", line 1036, in setUpClass
'database': db_name,
File "C:\python\venv\gbook\lib\site-packages\django\core\management\__init__.py", line 131, in call_command
return command.execute(*args, **defaults)
File "C:\python\venv\gbook\lib\site-packages\django\core\management\base.py", line 330, in execute
output = self.handle(*args, **options)
File "C:\python\venv\gbook\lib\site-packages\modeltranslation\management\commands\loaddata.py", line 61, in handle
return super(Command, self).handle(*fixture_labels, **options)
File "C:\python\venv\gbook\lib\site-packages\django\core\management\commands\loaddata.py", line 69, in handle
self.loaddata(fixture_labels)
File "C:\python\venv\gbook\lib\site-packages\django\core\management\commands\loaddata.py", line 109, in loaddata
self.load_label(fixture_label)
File "C:\python\venv\gbook\lib\site-packages\django\core\management\commands\loaddata.py", line 175, in load_label
obj.save(using=self.using)
File "C:\python\venv\gbook\lib\site-packages\django\core\serializers\base.py", line 205, in save
models.Model.save_base(self.object, using=using, raw=True, **kwargs)
File "C:\python\venv\gbook\lib\site-packages\django\db\models\base.py", line 838, in save_base
updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
File "C:\python\venv\gbook\lib\site-packages\django\db\models\base.py", line 905, in _save_table
forced_update)
File "C:\python\venv\gbook\lib\site-packages\django\db\models\base.py", line 955, in _do_update
return filtered._update(values) > 0
File "C:\python\venv\gbook\lib\site-packages\django\db\models\query.py", line 664, in _update
return query.get_compiler(self.db).execute_sql(CURSOR)
File "C:\python\venv\gbook\lib\site-packages\django\db\models\sql\compiler.py", line 1204, in execute_sql
cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
File "C:\python\venv\gbook\lib\site-packages\django\db\models\sql\compiler.py", line 899, in execute_sql
raise original_exception
File "C:\python\venv\gbook\lib\site-packages\django\db\models\sql\compiler.py", line 889, in execute_sql
cursor.execute(sql, params)
File "C:\python\venv\gbook\lib\site-packages\django\db\backends\utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "C:\python\venv\gbook\lib\site-packages\django\db\utils.py", line 94, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "C:\python\venv\gbook\lib\site-packages\django\utils\six.py", line 685, in reraise
raise value.with_traceback(tb)
File "C:\python\venv\gbook\lib\site-packages\django\db\backends\utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "C:\python\venv\gbook\lib\site-packages\django\db\backends\sqlite3\base.py", line 328, in execute
return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: Problem installing fixture 'C:\kvk\develop\Python\gbook\order\fixtures\AirportInfo.json': Could not load order.AirportInfo(pk=2411): no such table: GB_AIRPORT_INFO
迁移似乎不适用于并行操作，但是为什么呢？
文档说：“ --parallel”在单独的并行进程中运行测试。每个进程都有自己的数据库。而且我不需要更改我的代码即可使用它。
请帮我理解，我在做什么错了。
multiprocessing.cpu_count（）= 4
Django版本1.11.10
Python 3.6.5
答案 0 :(得分：2)
到目前为止，Windows上仍禁用并行运行。您可以在https://code.djangoproject.com/ticket/31169上跟踪保持此功能进展的故障单。
这是在Windows上禁用此选项的代码块：
def default_test_processes():
"""Default number of test processes when using the --parallel option."""
# The current implementation of the parallel test runner requires
# multiprocessing to start subprocesses with fork().
if multiprocessing.get_start_method() != 'fork':
return 1
try:
return int(os.environ['DJANGO_TEST_PROCESSES'])
except KeyError:
return multiprocessing.cpu_count()
答案 1 :(得分：1)
在Windows上尝试使用--parallel功能时，我遇到了类似的问题。
Django的documentation状态
此功能在Windows上不可用。它也不适用于Oracle数据库后端。
在Linux上运行相同的命令已成功完成。
答案 2 :(得分：1)
与MacOS和Python 3.8+相同的问题。您必须在settings.py文件顶部显式设置import multiprocessing; multiprocessing.set_start_method('fork')。但是一定要先了解副作用！