我有一个Django项目，我将在其中开始编写Selenium测试。第一个看起来像这样：
from django.contrib.staticfiles.testing import StaticLiveServerTestCase
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from core.models import User
from example import settings
BACH_EMAIL = "johann.sebastian.bach@classics.com"
PASSWORD = "password"
class TestImportCRMData(StaticLiveServerTestCase):
@classmethod
def setUpClass(cls):
super().setUpClass()
cls.webdriver = webdriver.Chrome()
cls.webdriver.implicitly_wait(10)
@classmethod
def tearDownClass(cls):
cls.webdriver.close()
cls.webdriver.quit()
super().tearDownClass()
def setUp(self):
self.admin = User.objects.create_superuser(email=BACH_EMAIL, password=PASSWORD)
def test_admin_tool(self):
self.webdriver.get(f"http://{settings.ADMIN_HOST}:{self.server_thread.port}/admin")
self.webdriver.find_element_by_id("id_username").send_keys(BACH_EMAIL)
self.webdriver.find_element_by_id("id_password").send_keys(PASSWORD)
self.webdriver.find_element_by_id("id_password").send_keys(Keys.RETURN)
self.webdriver.find_element_by_link_text("Users").click()
当我运行它时，测试通过但仍然以以下错误结束：
Traceback (most recent call last):
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\db\backends\utils.py", line 83, in _execute
return self.cursor.execute(sql)
psycopg2.OperationalError: database "test_example" is being accessed by other users
DETAIL: There is 1 other session using the database.
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "C:\Program Files\JetBrains\PyCharm 2018.2.4\helpers\pycharm\django_test_manage.py", line 168, in <module>
utility.execute()
File "C:\Program Files\JetBrains\PyCharm 2018.2.4\helpers\pycharm\django_test_manage.py", line 142, in execute
_create_command().run_from_argv(self.argv)
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\core\management\commands\test.py", line 26, in run_from_argv
super().run_from_argv(argv)
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\core\management\base.py", line 316, in run_from_argv
self.execute(*args, **cmd_options)
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\core\management\base.py", line 353, in execute
output = self.handle(*args, **options)
File "C:\Program Files\JetBrains\PyCharm 2018.2.4\helpers\pycharm\django_test_manage.py", line 104, in handle
failures = TestRunner(test_labels, **options)
File "C:\Program Files\JetBrains\PyCharm 2018.2.4\helpers\pycharm\django_test_runner.py", line 255, in run_tests
extra_tests=extra_tests, **options)
File "C:\Program Files\JetBrains\PyCharm 2018.2.4\helpers\pycharm\django_test_runner.py", line 156, in run_tests
return super(DjangoTeamcityTestRunner, self).run_tests(test_labels, extra_tests, **kwargs)
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\test\runner.py", line 607, in run_tests
self.teardown_databases(old_config)
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\test\runner.py", line 580, in teardown_databases
keepdb=self.keepdb,
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\test\utils.py", line 297, in teardown_databases
connection.creation.destroy_test_db(old_name, verbosity, keepdb)
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\db\backends\base\creation.py", line 257, in destroy_test_db
self._destroy_test_db(test_database_name, verbosity)
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\db\backends\base\creation.py", line 274, in _destroy_test_db
% self.connection.ops.quote_name(test_database_name))
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\db\backends\utils.py", line 68, in execute
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\db\backends\utils.py", line 77, in _execute_with_wrappers
return executor(sql, params, many, context)
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
return self.cursor.execute(sql, params)
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\db\utils.py", line 89, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "C:\Users\pupeno\Documents\Eligible\code\example\venv\lib\site-packages\django\db\backends\utils.py", line 83, in _execute
return self.cursor.execute(sql)
django.db.utils.OperationalError: database "test_example" is being accessed by other users
DETAIL: There is 1 other session using the database.
当然的问题是，下一次运行测试时，数据库仍然存在，因此，在不确认删除数据库的情况下不会运行测试。
如果我在最后一行注释掉：
self.webdriver.find_element_by_link_text("Users").click()
然后我没有收到此错误。我猜只是因为没有建立数据库连接。有时是另外1个会话，有时最多是4个会话。在4个会话的情况之一中，这些是正在运行的会话：
select * from pg_stat_activity where datname = 'test_example';
100123 test_example 29892 16393 pupeno "" ::1 61967 2018-11-15 17:28:19.552431 2018-11-15 17:28:19.562398 2018-11-15 17:28:19.564623 idle SELECT "core_user"."id", "core_user"."password", "core_user"."last_login", "core_user"."is_superuser", "core_user"."email", "core_user"."is_staff", "core_user"."is_active", "core_user"."date_joined" FROM "core_user" WHERE "core_user"."id" = 1
100123 test_example 33028 16393 pupeno "" ::1 61930 2018-11-15 17:28:18.792466 2018-11-15 17:28:18.843383 2018-11-15 17:28:18.851828 idle SELECT "django_admin_log"."id", "django_admin_log"."action_time", "django_admin_log"."user_id", "django_admin_log"."content_type_id", "django_admin_log"."object_id", "django_admin_log"."object_repr", "django_admin_log"."action_flag", "django_admin_log"."change_message", "core_user"."id", "core_user"."password", "core_user"."last_login", "core_user"."is_superuser", "core_user"."email", "core_user"."is_staff", "core_user"."is_active", "core_user"."date_joined", "django_content_type"."id", "django_content_type"."app_label", "django_content_type"."model" FROM "django_admin_log" INNER JOIN "core_user" ON ("django_admin_log"."user_id" = "core_user"."id") LEFT OUTER JOIN "django_content_type" ON ("django_admin_log"."content_type_id" = "django_content_type"."id") WHERE "django_admin_log"."user_id" = 1 ORDER BY "django_admin_log"."action_time" DESC LIMIT 10
100123 test_example 14128 16393 pupeno "" ::1 61988 2018-11-15 17:28:19.767225 2018-11-15 17:28:19.776150 2018-11-15 17:28:19.776479 idle SELECT "core_firm"."id", "core_firm"."name", "core_firm"."host_name" FROM "core_firm" WHERE "core_firm"."id" = 1
100123 test_example 9604 16393 pupeno "" ::1 61960 2018-11-15 17:28:19.469197 2018-11-15 17:28:19.478775 2018-11-15 17:28:19.478788 idle COMMIT
我一直在尝试找到此问题的最小可重现示例，但到目前为止，我还没有成功。
有什么想法会导致这种情况，或者如何找出有关此问题的更多信息？
答案 0 :(得分：4)
此错误消息...
django.db.utils.OperationalError: database "test_example" is being accessed by other users
DETAIL: There is 1 other session using the database.
...表示存在使用数据库的会话，而新会话无法访问数据库。
有关 Django 版本，数据库 type 和 version 的更多信息以及 Selenium ， ChromeDriver 和 Chrome 版本将有助于我们更好地调试此问题。
但是，您需要从硒角度考虑以下几点：
在下一轮测试中启动新会话时，您需要删除代码行cls.webdriver.close()，因为下一行代码cls.webdriver.quit()足以终止测试。现有会话。按照最佳做法，您应该在quit()中调用 tearDown() {} 方法。通过发送带有 {“ flags”：[“ eForceQuit”]的“退出” 命令，调用 quit() DELETE当前的浏览会话} ，最后在 /关闭 EndPoint上发送 GET 请求。下面是一个示例：
1503397488598 webdriver::server DEBUG -> DELETE /session/8e457516-3335-4d3b-9140-53fb52aa8b74
1503397488607 geckodriver::marionette TRACE -> 37:[0,4,"quit",{"flags":["eForceQuit"]}]
1503397488821 webdriver::server DEBUG -> GET /shutdown
因此，在调用 quit() 方法时，Web Browser会话和WebDriver实例将被完全杀死。因此，您无需合并任何其他步骤，而这将是一项开销。
您可以在Selenium : How to stop geckodriver process impacting PC memory, without calling driver.quit()?
中找到详细的讨论
因此您需要：
删除implicitly_wait(10)：
cls.webdriver.implicitly_wait(10)
在与元素交互时生成 WebDriverWait ：
WebDriverWait(driver, 20).until(EC.element_to_be_clickable((By.ID, "id_username"))).send_keys(BACH_EMAIL)
self.webdriver.find_element_by_id("id_password").send_keys(PASSWORD)
self.webdriver.find_element_by_id("id_password").send_keys(Keys.RETURN)
WebDriverWait(driver, 20).until(EC.element_to_be_clickable((By.LINK_TEXT, "Users"))).click()
现在，根据讨论Persistent connections not closed by LiveServerTestCase, preventing dropping test databases，已在 Djangov1.6 中发现，报告并讨论了此问题，并已修复。主要问题是：
只要将PostgreSQL连接标记为持久（
CONN_MAX_AGE = None）并执行LiveServerTestCase，就永远不会关闭服务器线程的连接，从而导致无法删除测试数据库。
这正是您看到的原因：
select * from pg_stat_activity where datname = 'test_example';
100123 test_example 29892 16393 pupeno "" ::1 61967 2018-11-15 17:28:19.552431 2018-11-15 17:28:19.562398 2018-11-15 17:28:19.564623 idle SELECT "core_user"."id", "core_user"."password", "core_user"."last_login", "core_user"."is_superuser", "core_user"."email", "core_user"."is_staff", "core_user"."is_active", "core_user"."date_joined" FROM "core_user" WHERE "core_user"."id" = 1
100123 test_example 33028 16393 pupeno "" ::1 61930 2018-11-15 17:28:18.792466 2018-11-15 17:28:18.843383 2018-11-15 17:28:18.851828 idle SELECT "django_admin_log"."id", "django_admin_log"."action_time", "django_admin_log"."user_id", "django_admin_log"."content_type_id", "django_admin_log"."object_id", "django_admin_log"."object_repr", "django_admin_log"."action_flag", "django_admin_log"."change_message", "core_user"."id", "core_user"."password", "core_user"."last_login", "core_user"."is_superuser", "core_user"."email", "core_user"."is_staff", "core_user"."is_active", "core_user"."date_joined", "django_content_type"."id", "django_content_type"."app_label", "django_content_type"."model" FROM "django_admin_log" INNER JOIN "core_user" ON ("django_admin_log"."user_id" = "core_user"."id") LEFT OUTER JOIN "django_content_type" ON ("django_admin_log"."content_type_id" = "django_content_type"."id") WHERE "django_admin_log"."user_id" = 1 ORDER BY "django_admin_log"."action_time" DESC LIMIT 10
100123 test_example 14128 16393 pupeno "" ::1 61988 2018-11-15 17:28:19.767225 2018-11-15 17:28:19.776150 2018-11-15 17:28:19.776479 idle SELECT "core_firm"."id", "core_firm"."name", "core_firm"."host_name" FROM "core_firm" WHERE "core_firm"."id" = 1
100123 test_example 9604 16393 pupeno "" ::1 61960 2018-11-15 17:28:19.469197 2018-11-15 17:28:19.478775 2018-11-15 17:28:19.478788 idle COMMIT
进一步观察到，即使使用CONN_MAX_AGE=None，在LiveServerTestCase.tearDownClass()之后，查询PostgreSQL的pg_stat_activity仍显示状态为 idle 的挥之不去的连接（这是连接由您的情况下的先前测试创建）。因此，很明显，当线程终止并且吸油针位于时，空闲连接不会关闭：
LiveServerThread(threading.Thread)，它们控制在测试运行时运行实时http服务器的线程：
class LiveServerThread(threading.Thread):
def __init__(self, host, static_handler, connections_override=None):
self.host = host
self.port = None
self.is_ready = threading.Event()
self.error = None
self.static_handler = static_handler
self.connections_override = connections_override
super(LiveServerThread, self).__init__()
def run(self):
"""
Sets up the live server and databases, and then loops over handling
http requests.
"""
if self.connections_override:
# Override this thread's database connections with the ones
# provided by the main thread.
for alias, conn in self.connections_override.items():
connections[alias] = conn
try:
# Create the handler for serving static and media files
handler = self.static_handler(_MediaFilesHandler(WSGIHandler()))
self.httpd = self._create_server(0)
self.port = self.httpd.server_address[1]
self.httpd.set_app(handler)
self.is_ready.set()
self.httpd.serve_forever()
except Exception as e:
self.error = e
self.is_ready.set()
def _create_server(self, port):
return WSGIServer((self.host, port), QuietWSGIRequestHandler, allow_reuse_address=False)
def terminate(self):
if hasattr(self, 'httpd'):
# Stop the WSGI server
self.httpd.shutdown()
self.httpd.server_close()
LiveServerTestCase(TransactionTestCase)基本上与TransactionTestCase相同，但是还会在单独的线程中启动活动的http服务器，以便测试可以使用 Selenium使用的另一个测试框架，而不是内置的虚拟客户端：
class LiveServerTestCase(TransactionTestCase):
host = 'localhost'
static_handler = _StaticFilesHandler
@classproperty
def live_server_url(cls):
return 'http://%s:%s' % (cls.host, cls.server_thread.port)
@classmethod
def setUpClass(cls):
super(LiveServerTestCase, cls).setUpClass()
connections_override = {}
for conn in connections.all():
# If using in-memory sqlite databases, pass the connections to
# the server thread.
if conn.vendor == 'sqlite' and conn.is_in_memory_db(conn.settings_dict['NAME']):
# Explicitly enable thread-shareability for this connection
conn.allow_thread_sharing = True
connections_override[conn.alias] = conn
cls._live_server_modified_settings = modify_settings(
ALLOWED_HOSTS={'append': cls.host},
)
cls._live_server_modified_settings.enable()
cls.server_thread = cls._create_server_thread(connections_override)
cls.server_thread.daemon = True
cls.server_thread.start()
# Wait for the live server to be ready
cls.server_thread.is_ready.wait()
if cls.server_thread.error:
# Clean up behind ourselves, since tearDownClass won't get called in
# case of errors.
cls._tearDownClassInternal()
raise cls.server_thread.error
@classmethod
def _create_server_thread(cls, connections_override):
return LiveServerThread(
cls.host,
cls.static_handler,
connections_override=connections_override,
)
@classmethod
def _tearDownClassInternal(cls):
# There may not be a 'server_thread' attribute if setUpClass() for some
# reasons has raised an exception.
if hasattr(cls, 'server_thread'):
# Terminate the live server's thread
cls.server_thread.terminate()
cls.server_thread.join()
# Restore sqlite in-memory database connections' non-shareability
for conn in connections.all():
if conn.vendor == 'sqlite' and conn.is_in_memory_db(conn.settings_dict['NAME']):
conn.allow_thread_sharing = False
@classmethod
def tearDownClass(cls):
cls._tearDownClassInternal()
cls._live_server_modified_settings.disable()
super(LiveServerTestCase, cls).tearDownClass()
解决方案是仅关闭非覆盖的连接，并从此pull request / commit引入。更改为：
在django/test/testcases.py中添加：
finally:
connections.close_all()
添加新文件tests/servers/test_liveserverthread.py：
from django.db import DEFAULT_DB_ALIAS, connections
from django.test import LiveServerTestCase, TestCase
class LiveServerThreadTest(TestCase):
def run_live_server_thread(self, connections_override=None):
thread = LiveServerTestCase._create_server_thread(connections_override)
thread.daemon = True
thread.start()
thread.is_ready.wait()
thread.terminate()
def test_closes_connections(self):
conn = connections[DEFAULT_DB_ALIAS]
if conn.vendor == 'sqlite' and conn.is_in_memory_db():
self.skipTest("the sqlite backend's close() method is a no-op when using an in-memory database")
# Pass a connection to the thread to check they are being closed.
connections_override = {DEFAULT_DB_ALIAS: conn}
saved_sharing = conn.allow_thread_sharing
try:
conn.allow_thread_sharing = True
self.assertTrue(conn.is_usable())
self.run_live_server_thread(connections_override)
self.assertFalse(conn.is_usable())
finally:
conn.allow_thread_sharing = saved_sharing
在tests/servers/tests.py中删除：
finally:
TestCase.tearDownClass()
在tests/servers/tests.py中添加：
finally:
if hasattr(TestCase, 'server_thread'):
TestCase.server_thread.terminate()
步骤：
答案 1 :(得分：0)
检查活动连接以了解导致问题的原因
select * from pg_stat_activity;
您可以禁用扩展程序：
@classmethod
def setUpClass(cls):
super().setUpClass()
options = webdriver.chrome.options.Options()
options.add_argument("--disable-extensions")
cls.webdriver = webdriver.Chrome(chrome_options=options)
cls.webdriver.implicitly_wait(10)
然后拆解：
@classmethod
def tearDownClass(cls):
cls.webdriver.stop_client()
cls.webdriver.quit()
connections.close_all()
super().tearDownClass()
答案 2 :(得分：0)
有报道称早就出现了同样的问题
https://code.djangoproject.com/ticket/22414
您需要确保的一件事是将CONN_MAX_AGE设置为0而不是None
此外，您可以在拆卸中使用以下类似内容
@classmethod
def tearDownClass(cls):
# Workaround for https://code.djangoproject.com/ticket/22414
# Persistent connections not closed by LiveServerTestCase, preventing dropping test databases
# https://github.com/cjerdonek/django/commit/b07fbca02688a0f8eb159f0dde132e7498aa40cc
def close_sessions(conn):
close_sessions_query = """
SELECT pg_terminate_backend(pg_stat_activity.pid) FROM pg_stat_activity WHERE
datname = current_database() AND
pid <> pg_backend_pid();
"""
with conn.cursor() as cursor:
try:
cursor.execute(close_sessions_query)
except OperationalError:
# We get kicked out after closing.
pass
for alias in connections:
connections[alias].close()
close_sessions(connections[alias])
print "Forcefully closed database connections."
以上代码来自URL下方