python - celery 与 SQLite : AttributeError: 'DisabledBackend' object has no attribute '_get_task_meta_for'

Question

我想研究celery项目，但是不知道哪里出错了。“tasks.py”文件:

# -*- coding: utf-8 -*-
from celery import Celery

app = Celery('tasks', broker='sqla+sqlite:///celerydb.sqlite')
app.conf.update(
    CELERY_RESULT_BACKEND = 'db+sqlite:///results.sqlite',
#   CELERY_RESULT_BACKEND = 'redis://localhost/0',
#   CELERY_RESULT_BACKEND = 'amqp',
#   CELERY_RESULT_BACKEND = 'mongodb://127.0.0.1:27017/',
    CELERY_TASK_SERIALIZER = 'json',
    CELERY_IGNORE_RESULT = False,
    )

@app.task(trail=True)
def add(x, y):
    return x + y

@app.task(trail=True)
def mul(x, y):
    return x * y

@app.task(trail=True)
def xsum(numbers):
    return sum(numbers)

然后我像这样运行 celery 服务:

celery -A tasks worker --loglevel=info  

效果很好。然后我使用 ipython 运行流程脚本:

In [127]: result = add.delay(3,5)
In [128]: result.result

这样的错误:

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-128-a030fb181312> in <module>()
----> 1 result.result

/home/xingming/pyvirt/local/lib/python2.7/site-packages/celery/result.pyc in result(self)
    350         If the task raised an exception, this will be the exception
    351         instance."""
--> 352         return self._get_task_meta()['result']
    353     info = result
    354 

/home/xingming/pyvirt/local/lib/python2.7/site-packages/celery/result.pyc in _get_task_meta(self)
    326     def _get_task_meta(self):
    327         if self._cache is None:
--> 328             meta = self.backend.get_task_meta(self.id)
    329             if meta:
    330                 state = meta['status']

/home/xingming/pyvirt/local/lib/python2.7/site-packages/celery/backends/base.pyc in get_task_meta(self, task_id, cache)
    292                 pass
    293 
--> 294         meta = self._get_task_meta_for(task_id)
    295         if cache and meta.get('status') == states.SUCCESS:
    296             self._cache[task_id] = meta

AttributeError: 'DisabledBackend' object has no attribute '_get_task_meta_for'

但是 celery 服务运行良好:

[2014-06-04 11:17:31,656: INFO/MainProcess] Received task: tasks.add[11baa65f-4e18-44b1-80e4-9e81626ca42a]
[2014-06-04 11:17:31,658: INFO/MainProcess] Task tasks.add[11baa65f-4e18-44b1-80e4-9e81626ca42a] succeeded in 0.00117350020446s: 8

这有什么问题吗？

感谢您的帮助!

Answer 1

你没有搞错。 Celery docs充分解释一下:默认情况下，存储任务结果的后端未启用，因此您无法使用任何使用它的函数。如果您想这样做，您需要按照文档配置后端。