启动服务器时Django中的_DeadlockError

Question

很多时候我在启动python服务器时遇到此错误。当我更改任何文件并且服务器再次启动时，也会发生这种情况。

我尝试删除环境并重新创建环境，但是仍然存在相同的错误。

Linux上的Python 3.5.2（默认值，2018年11月12日，13：43：14）[GCC 5.4.0 20160609]

的Django：2.2.1

/home/satyam/Code/myproject/myproject_apps/invoice/services/excel_service.py changed, reloading.
Watching for file changes with StatReloader
Performing system checks...

Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/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/lib/python3.5/threading.py", line 914, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.5/threading.py", line 862, in run
    self._target(*self._args, **self._kwargs)
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/utils/autoreload.py", line 54, in wrapper
    fn(*args, **kwargs)
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/core/management/commands/runserver.py", line 117, in inner_run
    self.check(display_num_errors=True)
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/core/management/base.py", line 390, in check
    include_deployment_checks=include_deployment_checks,
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/core/management/base.py", line 377, in _run_checks
    return checks.run_checks(**kwargs)
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/core/checks/registry.py", line 72, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/contrib/admin/checks.py", line 79, in check_dependencies
    for engine in engines.all():
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/template/utils.py", line 90, in all
    return [self[alias] for alias in self]
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/template/utils.py", line 90, in <listcomp>
    return [self[alias] for alias in self]
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/template/utils.py", line 81, in __getitem__
    engine = engine_cls(params)
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/template/backends/django.py", line 25, in __init__
    options['libraries'] = self.get_templatetag_libraries(libraries)
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/template/backends/django.py", line 43, in get_templatetag_libraries
    libraries = get_installed_libraries()
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/template/backends/django.py", line 108, in get_installed_libraries
    for name in get_package_libraries(pkg):
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/template/backends/django.py", line 121, in get_package_libraries
    module = import_module(entry[1])
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 665, in exec_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/rest_framework/templatetags/rest_framework.py", line 15, in <module>
    from rest_framework.renderers import HTMLFormRenderer
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/rest_framework/renderers.py", line 20, in <module>
    from django.test.client import encode_multipart
  File "/home/satyam/Code/environments/ebapps/lib/python3.5/site-packages/django/test/client.py", line 23, in <module>
    from django.test import signals
  File "<frozen importlib._bootstrap>", line 968, in _find_and_load
  File "<frozen importlib._bootstrap>", line 168, in __enter__
  File "<frozen importlib._bootstrap>", line 110, in acquire
_frozen_importlib._DeadlockError: deadlock detected by _ModuleLock('django.test.signals') at 140078699689688

Answer 1

看起来您有死锁，因为从信号处理程序发送信号到同一模型。或者第二个处理程序等待第一个处理程序解锁某些资源。行或表很可能在数据库级别被锁定。