'Celery raises ValueError: not enough values to unpack

Trying to run simple example with Celery and receiving an exception. RabbitMQ started in a Docker, also tried to start it locally. Celery works on a local Windows host

from celery import Celery

app = Celery('tasks', broker='amqp://192.168.99.100:32774')

@app.task()
def hello():
    print('hello')


if __name__ == '__main__':
    hello.delay()

Excerpt of my error text:

[2017-08-18 00:01:08,632: ERROR/MainProcess] Task handler raised error: ValueError('not enough values to unpack (expected 3, got 0)',)
Traceback (most recent call last):                                              
    File "c:\users\user\celenv\lib\site-packages\billiard\pool.py", line 358, in workloop                        
        result = (True, prepare_result(fun(*args, **kwargs)))                                  
    File "c:\users\user\celenv\lib\site-packages\celery\app\trace.py", line 525, in _fast_trace_task
        tasks, accept, hostname = _loc
ValueError: not enough values to unpack (expected 3, got 0)

python celery

Solution 1:^[1]

Celery 4.0+ does not officially support Windows yet. But it still works on Windows for some development/test purposes.

Use eventlet instead as below:

pip install eventlet
celery -A <module> worker -l info -P eventlet

It works for me on Windows 10 + celery 4.1 + python 3.

===== update 2018-11 =====

Eventlet has an issue on subprocess.CalledProcessError:

https://github.com/celery/celery/issues/4063

https://github.com/eventlet/eventlet/issues/357

https://github.com/eventlet/eventlet/issues/413

So try gevent instead.

pip install gevent
celery -A <module> worker -l info -P gevent

This works for me on Windows 10 + celery 4.2 + python 3.6

Solution 2:^[2]

I got this error on Windows 7 32bit system. So I did this to make it work.

Add this

`os.environ.setdefault('FORKED_BY_MULTIPROCESSING', '1')`

before defining a celery instance in myproj/settings.py file in your django project.

It should like like

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'myproj.settings')
os.environ.setdefault('FORKED_BY_MULTIPROCESSING', '1')

app = Celery('tasks', broker='redis://127.0.0.1:6379/0')

I am using redis as a messaging broker so defined broker='redis://127.0.0.1:6379/0'

Solution 3:^[3]

For Celery 4.1 on Windows.

Set an environment variable FORKED_BY_MULTIPROCESSING=1. Then you can simply run celery -A <celery module> worker.

Solution 4:^[4]

It worked for me:

celery -A my_project_name worker --pool=solo -l info

basically things become single threaded and are suppoted

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	pushrbx
Solution 2	Lawrence Gandhar
Solution 3	Bob Jordan
Solution 4	Sourabh SInha

'Celery raises ValueError: not enough values to unpack

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Sources

Related Questions

Solution 1:^[1]

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