Python Celery - How to call celery tasks inside other task

问题:

I'm calling a task within a tasks in Django-Celery

Here are my tasks.

@shared_task def post_notification(data,url):     url = "http://posttestserver.com/data/?dir=praful" # when in production, remove this line.     headers = {'content-type': 'application/json'}     requests.post(url, data=json.dumps(data), headers=headers)   @shared_task def shipment_server(data,notification_type):     notification_obj = Notification.objects.get(name = notification_type)     server_list = ServerNotificationMapping.objects.filter(notification_name=notification_obj)      for server in server_list:         task = post_notification.delay(data,server.server_id.url)         print task.status # it prints 'Nonetype' has no attribute id 

How can I call a task within a task? I read somewhere it can be done using group, but I'm not able to form the correct syntax. How do I do it?

I tried this

for server in server_list:     task = group(post_notification.s(data, server.server_id.url))().get()     print task.status 

Throws a warning saying

TxIsolationWarning: Polling results w│                                                                         ith transaction isolation level repeatable-read within the same transacti│                                                                         on may give outdated results. Be sure to commit the transaction for each │                                                                         poll iteration.                                                          │                                                                           'Polling results with transaction isolation level ' 

Dont know what it is!!!

How do I solve my problem?

回答1:

This should work:

celery.current_app.send_task('mymodel.tasks.mytask', args=[arg1, arg2, arg3]) 

回答2:

You are right, because each task in you for loop will be overwrite task variable.

You can try celery.group like

from celery import group 

and

@shared_task def shipment_server(data,notification_type):     notification_obj = Notification.objects.get(name = notification_type)     server_list = ServerNotificationMapping.objects.filter(notification_name=notification_obj)       tasks = [post_notification.s(data, server.server_id.url) for server in server_list]     results = group(tasks)()     print results.get() # results.status() what ever you want 

回答3:

you can call task from a task using delay function

from app.tasks import celery_add_task     celery_add_task.apply_async(args=[task_name])  

... it will work

文章来源: Python Celery - How to call celery tasks inside other task