为什么芹菜5需要djcelery？

Question

我正在执行芹菜documentation所说的。

celery.py

import os

from celery import Celery

# set the default Django settings module for the 'celery' program.
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'proj.settings')
broker = 'sqla+postgresql://user:pass@localhost/db'

app = Celery('proj', broker=broker)

# Using a string here means the worker doesn't have to serialize
# the configuration object to child processes.
# - namespace='CELERY' means all celery-related configuration keys
#   should have a `CELERY_` prefix.
app.config_from_object('django.conf:settings', namespace='CELERY')

# Load task modules from all registered Django app configs.
app.autodiscover_tasks()


@app.task(bind=True)
def debug_task(self):
    print(f'Request: {self.request!r}')

我所面临的错误。

[2021-05-18 03:21:29,974: CRITICAL/MainProcess] Unrecoverable error: ModuleNotFoundError("No module named 'djcelery'")
Traceback (most recent call last):
  File "/Users/proj/venv/lib/python3.9/site-packages/celery/app/base.py", line 1211, in backend
    return self._local.backend
AttributeError: '_thread._local' object has no attribute 'backend'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/proj/venv/lib/python3.9/site-packages/celery/worker/worker.py", line 203, in start
    self.blueprint.start(self)
  File "/Users/proj/venv/lib/python3.9/site-packages/celery/bootsteps.py", line 112, in start
    self.on_start()
  File "/Users/proj/venv/lib/python3.9/site-packages/celery/apps/worker.py", line 136, in on_start
    self.emit_banner()
  File "/Users/proj/venv/lib/python3.9/site-packages/celery/apps/worker.py", line 170, in emit_banner
    ' \n', self.startup_info(artlines=not use_image))),
  File "/Users/proj/venv/lib/python3.9/site-packages/celery/apps/worker.py", line 232, in startup_info
    results=self.app.backend.as_uri(),
  File "/Users/proj/venv/lib/python3.9/site-packages/celery/app/base.py", line 1213, in backend
    self._local.backend = new_backend = self._get_backend()
  File "/Users/proj/venv/lib/python3.9/site-packages/celery/app/base.py", line 916, in _get_backend
    backend, url = backends.by_url(
  File "/Users/proj/venv/lib/python3.9/site-packages/celery/app/backends.py", line 70, in by_url
    return by_name(backend, loader), url
  File "/Users/proj/venv/lib/python3.9/site-packages/celery/app/backends.py", line 50, in by_name
    cls = symbol_by_name(backend, aliases)
  File "/Users/proj/venv/lib/python3.9/site-packages/kombu/utils/imports.py", line 56, in symbol_by_name
    module = imp(module_name, package=package, **kwargs)
  File "/usr/local/Cellar/python@3.9/3.9.4/Frameworks/Python.framework/Versions/3.9/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 972, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 972, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 984, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'djcelery'

现在，如果我安装djanog-celery，那么它最终卸载了celery 5并安装了celery 3.1。文档中说，celery 5不需要安装任何其他库。不确定为什么需要此依赖项。

下面是pip freeze命令的输出

amqp==5.0.6
anyjson==0.3.3
appnope==0.1.2
asgiref==3.3.1
backcall==0.2.0
billiard==3.6.4.0
celery==5.0.5
certifi==2020.12.5
chardet==4.0.0
click==7.1.2
click-didyoumean==0.0.3
click-plugins==1.1.1
click-repl==0.1.6
decorator==4.4.2
Django==3.1.7
django-choices==1.7.1
django-cors-headers==3.7.0
djangorestframework==3.12.4
greenlet==1.1.0
idna==2.10
ipython==7.21.0
ipython-genutils==0.2.0
jedi==0.18.0
kombu==5.0.2
numpy==1.20.1
pandas==1.2.3
pandas-ta==0.2.45b0
parso==0.8.1
pexpect==4.8.0
pickleshare==0.7.5
prompt-toolkit==3.0.16
psycopg2==2.8.6
ptyprocess==0.7.0
Pygments==2.8.1
python-dateutil==2.8.1
python-memcached==1.59
pytz==2021.1
requests==2.25.1
scipy==1.6.1
six==1.15.0
SQLAlchemy==1.4.15
sqlparse==0.4.1
technical-indicators-lib==0.0.2
tqdm==4.59.0
traitlets==5.0.5
urllib3==1.26.3
vine==5.0.0
wcwidth==0.2.5
XlsxWriter==1.3.9

Answer 1

您的芹菜版本是5.0或更高，但是the latest djcelery版本只有3.3.1，版本不匹配，Django似乎不再支持3.3 django-celery之后的芹菜版本。

尽管文档中说celery 5不需要安装任何其他库，但似乎如果您通过API添加定时任务，则必须使用django-celery。如果你只是在设置文件中静态地设置定时任务，你不需要django- celery，只要芹菜就足够了。如果您必须通过API添加定时任务，我建议使用其他库，如: django-apscheduler或django-crontab。