How to troubleshoot an "AttributeError: __exit__" in multiproccesing in Python?
Solution 1:
The problem is in this line:
with pattern.findall(row) as f:
You are using the with
statement. It requires an object with __enter__
and __exit__
methods. But pattern.findall
returns a list
, with
tries to store the __exit__
method, but it can't find it, and raises an error. Just use
f = pattern.findall(row)
instead.
Solution 2:
It is not the asker's problem in this instance but the first troubleshooting step for a generic "AttributeError: __exit__" should be making sure the brackets are there, e.g.
with SomeContextManager() as foo:
#works because a new object is referenced...
not
with SomeContextManager as foo:
#AttributeError because the class is referenced
Catches me out from time to time and I end up here -__-
Solution 3:
The error also happens when trying to use the
with multiprocessing.Pool() as pool:
# ...
with a Python version that is too old (like Python 2.X) and does not support using with
together with multiprocessing pools.
(See this answer https://stackoverflow.com/a/25968716/1426569 to another question for more details)