Question

我有一个简单的应用程序，其中同时使用了django和django-rest-framework。

经常，当我尝试启动本地服务器（python manage.py runserver）时，出现以下异常：

Watching for file changes with StatReloader
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/project/venv/lib/python3.7/site-packages/django/template/utils.py", line 66, in __getitem__
    return self._engines[alias]
KeyError: 'django'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/Cellar/python/3.7.2_2/Frameworks/Python.framework/Versions/3.7/lib/python3.7/threading.py", line 917, in _bootstrap_inner
    self.run()
  File "/usr/local/Cellar/python/3.7.2_2/Frameworks/Python.framework/Versions/3.7/lib/python3.7/threading.py", line 865, in run
    self._target(*self._args, **self._kwargs)
  File "/project/venv/lib/python3.7/site-packages/django/utils/autoreload.py", line 54, in wrapper
    fn(*args, **kwargs)
  File "/project/venv/lib/python3.7/site-packages/django/core/management/commands/runserver.py", line 117, in inner_run
    self.check(display_num_errors=True)
  File "/project/venv/lib/python3.7/site-packages/django/core/management/base.py", line 390, in check
    include_deployment_checks=include_deployment_checks,
  File "/project/venv/lib/python3.7/site-packages/django/core/management/base.py", line 377, in _run_checks
    return checks.run_checks(**kwargs)
  File "/project/venv/lib/python3.7/site-packages/django/core/checks/registry.py", line 72, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/project/venv/lib/python3.7/site-packages/django/contrib/admin/checks.py", line 80, in check_dependencies
    for engine in engines.all():
  File "/project/venv/lib/python3.7/site-packages/django/template/utils.py", line 90, in all
    return [self[alias] for alias in self]
  File "/project/venv/lib/python3.7/site-packages/django/template/utils.py", line 90, in <listcomp>
    return [self[alias] for alias in self]
  File "/project/venv/lib/python3.7/site-packages/django/template/utils.py", line 81, in __getitem__
    engine = engine_cls(params)
  File "/project/venv/lib/python3.7/site-packages/django/template/backends/django.py", line 25, in __init__
    options['libraries'] = self.get_templatetag_libraries(libraries)
  File "/project/venv/lib/python3.7/site-packages/django/template/backends/django.py", line 43, in get_templatetag_libraries
    libraries = get_installed_libraries()
  File "/project/venv/lib/python3.7/site-packages/django/template/backends/django.py", line 108, in get_installed_libraries
    for name in get_package_libraries(pkg):
  File "/project/venv/lib/python3.7/site-packages/django/template/backends/django.py", line 121, in get_package_libraries
    module = import_module(entry[1])
  File "/project/venv/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/project/venv/lib/python3.7/site-packages/rest_framework/templatetags/rest_framework.py", line 15, in <module>
    from rest_framework.renderers import HTMLFormRenderer
  File "/project/venv/lib/python3.7/site-packages/rest_framework/renderers.py", line 20, in <module>
    from django.test.client import encode_multipart
  File "/project/venv/lib/python3.7/site-packages/django/test/client.py", line 23, in <module>
    from django.test import signals
  File "<frozen importlib._bootstrap>", line 980, in _find_and_load
  File "<frozen importlib._bootstrap>", line 149, in __enter__
  File "<frozen importlib._bootstrap>", line 94, in acquire
_frozen_importlib._DeadlockError: deadlock detected by _ModuleLock('django.test.signals') at 4420467792

Performing system checks...

重试几次后，服务器成功启动。因此，它不是止步不前，但很烦人。

由于我是Django的新手，所以我想知道是否有防止这种错误的方法。

Answer 1

我遇到了同样的问题，无法可靠地复制它。我尝试删除.pyc文件，但仍然遇到相同的问题。我将“ rest_framework”移到了INSTALLED_APPS列表的末尾，这似乎对我有用。

Answer 2

该错误是由于Django Rest Framework引起的，您可以通过将其删除并查看错误是否消失来进行检查。更具体地说，就我而言，只需删除

from rest_framework.urlpatterns import format_suffix_patterns

urls.py中的

解决了该问题，并且仍安装了Django Rest Framework。

Answer 3

我遇到了同样的问题，我还不知道如何重现它以及它为什么会发生。但这似乎与Django新版本有关。

从this comment开始，似乎是与虚拟环境中的.pyc文件有关的问题。

要解决此问题，这就是我所做的：

使用以下命令删除项目中的所有.pyc文件：find . -regex '*.pyc' -delete
停用虚拟环境并重新激活它。

问题消失了

尝试启动服务器时检测到死锁

3 个答案: