在 Django 中调用 .delay() 后，Celery 任务挂起

Question

从 django 应用程序调用导入任务的 .delay() 方法时，进程卡住，请求永远不会完成。

我们在控制台上也没有收到任何错误。 使用 pdb 设置 set_trace() 会产生同样的结果。

审查了以下问题，但未能帮助解决问题：

Calling celery task hangs for delay and apply_async

celery .delay hangs (recent, not an auth problem)

例如：

后端/settings.py

CELERY_BROKER_URL = os.environ.get("CELERY_BROKER", RABBIT_URL)
CELERY_RESULT_BACKEND = os.environ.get("CELERY_BROKER", RABBIT_URL)

后端/celery.py

from __future__ import absolute_import, unicode_literals

import os

from celery import Celery

# set the default Django settings module for the 'celery' program.
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'backend.settings')

app = Celery('backend')

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('Request: {0!r}'.format(self.request))

app/tasks.py

import time
from celery import shared_task

@shared_task
def upload_file(request_id):
    time.sleep(request_id)
    return True

app/views.py

from rest_framework.views import APIView

from .tasks import upload_file

class UploadCreateAPIView(APIView):
    # other methods...

    def post(self, request, *args, **kwargs):
        id = request.data.get("id", None)
        # business logic ...
        print("Going to submit task.")
        import pdb; pdb.set_trace()
        upload_file.delay(id)                  # <- this hangs the runserver as well as the set_trace()
        print("Submitted task.")

Answer 1

问题在于使用 Django 设置 celery 应用程序。我们需要确保在以下文件中导入并初始化了 celery 应用程序：

backend\__init__.py

from __future__ import absolute_import, unicode_literals

# This will make sure the app is always imported when
# Django starts so that shared_task will use this app.
from .celery import app as celery_app

__all__ = ('celery_app',)