找出celery任务是否存在

发送任务时，Celery不会写状态，这部分是一种优化（请参阅http://docs.celeryproject.org/en/latest/userguide/tasks.html#state）。

如果您确实需要它，添加起来很简单：

from celery import current_app# `after_task_publish` is available in celery 3.1+# for older versions use the deprecated `task_sent` signalfrom celery.signals import after_task_publish# when using celery versions older than 4.0, use body instead of headers@after_task_publish.connectdef 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，以检测是否已（似乎）未发送任务：

>>> result.state != "PENDING"