[Python] Celery raise ImproperlyConfigured exception

I am testing below case in Celery doc, but raise ImproperlyConfigured exception. http://docs.celeryproject.org/en/master/userguide/calling.html#id3

Traceback (most recent call last):
File "test.py", line 8, in <module> print(r.get(on_message=on_raw_message, propagate=False))
File "/usr/local/python2.7/lib/python2.7/site-packages/celery/result.py", line 189, in get on_message=on_message,
File "/usr/local/python2.7/lib/python2.7/site-packages/celery/backends/base.py", line 460, in wait_for_pending 'Backend does not support on_message callback')
celery.exceptions.ImproperlyConfigured: Backend does not support on_message callback


Test code is:

from celery_test.agent import hello
from celery_test.celery import app

def on_raw_message(body):
print(body)

r = hello.apply_async(args=[122,34], queue='machine1', routing_key='machine1')
print(r.get(on_message=on_raw_message, propagate=False))


Output of celery -A celery_test report

[root@zm03 script]# celery -A celery_test report

software -> celery:4.0.0 (latentcall) kombu:4.0.0 py:2.7.9
billiard:3.5.0.2 py-amqp:2.1.1
platform -> system:Linux arch:64bit, ELF imp:CPython
loader -> celery.loaders.app.AppLoader
settings -> transport:amqp results:amqp://guest@192.168.1.201//

CELERY_DEFAULT_EXCHANGE_TYPE: 'direct'
CELERY_RESULT_SERIALIZER: 'json'
timedelta: <type 'datetime.timedelta'>
Exchange: <class 'kombu.entity.Exchange'>
CELERY_INCLUDE: ['celery_test.agent']
absolute_import: _Feature((2, 5, 0, 'alpha', 1), (3, 0, 0, 'alpha', 0), 16384)
Queue: <class 'kombu.entity.Queue'>
CELERY_TASK_RESULT_EXPIRES: 3600
CELERT_QUEUES:
(<unbound Queue machine1 -> 'agent' -> machine1>,
<unbound Queue machine2 -> 'agent' -> machine2>)
CELERY_ACCEPT_CONTENT: ['json']
CELERY_TASK_SERIALIZER: 'json'
BROKER_URL: u'amqp://guest:********@192.168.1.201:5672//'
CELERY_RESULT_BACKEND: u'amqp://guest@192.168.1.201//'
CELERY_DEFAULT_EXCHANGE: 'agent'

Continue reading...