Celery任务组未在后台执行，并导致异常 [英] Celery task group not being executed in background and results in exception

问题描述

我的Celery任务未在我的Django 1.7/Python3项目中的后台执行.

My Celery task isn't executing in the background in my Django 1.7/Python3 project.

# settings.py

BROKER_URL = 'redis://localhost:6379/0'
CELERY_RESULTBACKEND = BROKER_URL
CELERYBEAT_SCHEDULER = 'djcelery.schedulers.DatabaseScheduler'
CELERY_ALWAYS_EAGER = False

我的根应用模块中有 celery.py ，例如:

I have celery.py in my root app module as such:

from __future__ import absolute_import

import os
import django

from celery import Celery
from django.conf import settings

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'my_app.settings')
django.setup()

app = Celery('my_app')
app.config_from_object('django.conf:settings')
app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)

并在根模块的 __ init __.py 中加载应用程序:

and load the app in __init__.py in the root module:

from __future__ import absolute_import
from .celery import app as celery_app

我的任务在我的应用程序模块中的task.py文件中设置为共享任务:

My task is set up as a shared task in a tasks.py file in my app module:

from __future__ import absolute_import
from celery import shared_task

@shared_task
def update_statistics(profile, category):
    # more code

然后我将该任务称为一个小组:

and I call the task as a group:

. . .
job = group([update_statistics(f.profile, category)
          for f in forecasts])
job.apply_async()

但是，我在任务队列中没有看到任何状态更新，而我正在通过以下方式启动

However, I'm not seeing any status updates in my task queue, which I am starting via:

$ celery -A my_app worker -l info

正在执行任务 ，只是不在后台执行.如果在任务代码中添加一条打印语句，我将在Django开发服务器控制台中看到输出，而不是Celery队列.

The task is being executed, just not in the background. If I add a print statement to the task code, I will see the output in my Django development server console instead of the Celery queue.

任务在前台运行后，我遇到了以下异常:

After the task runs in the foreground, I'm greeted with this exception:

'NoneType' object has no attribute 'app'

如果您有兴趣，这里是完整的追溯: https://gist.github.com/alsoicode/0263d251e3744227ba46

Here's the full traceback if you're interested: https://gist.github.com/alsoicode/0263d251e3744227ba46

推荐答案

创建组时，您直接在列表理解中调用任务，因此它们会在那里执行.您需要使用 .subtask()方法(或其快捷方式 .s())来创建子任务而不调用它们:

You're calling the tasks directly in your list comprehension when you create the group, so they're executed then and there. You need to use the .subtask() method (or its shortcut, .s()) to create the subtasks without calling them:

job = group([update_statistics.s(f.profile, category) for f in forecasts])

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