找出芹菜任务是否存在 [英] Find out whether celery task exists

问题描述

是否可以找出具有特定任务ID的任务是否存在？

Is it possible to find out whether a task with a certain task id exists? When I try to get the status, I will always get pending.

>>> AsyncResult('...').status
'PENDING'

我想知道给定的任务ID是否是真正的芹菜任务ID，而不是随机字符串。我想要不同的结果，具体取决于是否有某个特定ID的有效任务。

I want to know whether a given task id is a real celery task id and not a random string. I want different results depending on whether there is a valid task for a certain id.

过去可能有一个具有相同ID的有效任务，但结果可能已从后端删除。

There may have been a valid task in the past with the same id but the results may have been deleted from the backend.

推荐答案

在任务发送时，Celery不会写状态，这部分是优化
（请参见 http://docs.celeryproject.org/en /latest/userguide/tasks.html#state ）。

Celery does not write a state when the task is sent, this is partly an optimization (see http://docs.celeryproject.org/en/latest/userguide/tasks.html#state).

如果确实需要，添加以下内容很简单：

If you really need it, it's simple to add:

from celery import current_app
# `after_task_publish` is available in celery 3.1+
# for older versions use the deprecated `task_sent` signal
from celery.signals import after_task_publish

# when using celery versions older than 4.0, use body instead of headers

@after_task_publish.connect
def update_sent_state(sender=None, headers=None, **kwargs):
    # the task may not exist if sent using `send_task` which
    # sends tasks by name, so fall back to the default result backend
    # if that is the case.
    task = current_app.tasks.get(sender)
    backend = task.backend if task else current_app.backend

    backend.store_result(headers['id'], None, "SENT")

然后，您可以测试PENDING状态以检测任务是否尚未完成（貌似）
已发送：

Then you can test for the PENDING state to detect that a task has not (seemingly) been sent:

>>> result.state != "PENDING"

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