I am using python 2.7 multiprocessing on windows 7:
import multiprocessing as mp from Queue import Queue from multiprocessing.managers import AutoProxy if __name__ == '__main__': manager = mp.Manager() myqueue = manager.Queue() print myqueue print type(myqueue) print isinstance(myqueue, Queue) print isinstance(myqueue, AutoProxy)
<Queue.Queue instance at 0x0000000002956B08> <class 'multiprocessing.managers.AutoProxy[Queue]'> False Traceback (most recent call last): File "C:/Users/User/TryHere.py", line 12, in <module> print isinstance(myqueue, AutoProxy) TypeError: isinstance() arg 2 must be a class, type, or tuple of classes and types
My question is: I would like to check if a variable is an instance of a multiprocessing queue, how should i go about checking?
I have referred to:
but they dont seem to address my issue. Thanks in advance!
Question: I would like to check if a variable is an instance of a multiprocessing queue, how should i go about checking?
It’s a Proxy object,
multiprocessing.managers.BaseProxy does match:
from multiprocessing.managers import BaseProxy print(isinstance(myqueue, BaseProxy)) >>>True
Tested with Python: 3.4.2 and 2.7.9
Here’s what I do:
import multiprocessing as mp my_queue = mp.Queue() print(type(my_queue) == type(mp.Queue())) >>>True
For Python 3.6, the equivalent would be
import multiprocessing test_queue = multiprocessing.Queue() type(test_queue) == multiprocessing.queues.Queue: >>> True
We can choose not to perform a type-check upon a newly created Queue object as proposed by @mikeye
For Python 3.10, we can use the Queue under the
queues namespace, while still using
import multiprocessing as mp my_q = mp.Queue() isinstance(my_q, mp.queues.Queue) >>> True import asyncio isinstance(my_q, asyncio.Queue) >>> False import queue isinstance(my_q, queue.Queue) >>> False
I know this doesn’t exactly cover the original question, but since the error is much the same as with only using
mp.Queue instead of
mp.queues.Queue, I thought I’d add this.