Opened 9 years ago
Closed 8 years ago
#25862 closed Bug (wontfix)
LazyObject doesn't support multiprocessing on Python 2
Reported by: | Johannes Maron | Owned by: | nobody |
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Component: | Core (Other) | Version: | dev |
Severity: | Normal | Keywords: | py2 |
Cc: | info@… | Triage Stage: | Accepted |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description (last modified by )
Initial summary: AttributeError: 'FileSystemStorage' object has no attribute 'location'
I don't really want to bug anyone with python 2.7, for I couldn't care less. But, I stumbled upon something rather odd.
Easiest is to just check out the error on travis including the stack trace:
https://travis-ci.org/codingjoe/django-stdimage/builds/94713726
Everything works fine in Python 3, the attribute is available, as it should. It it's an instance attribute and properly set in the __init__
method:
https://github.com/django/django/blob/master/django/core/files/storage.py#L169-L172
I guess the error is here:
https://github.com/django/django/blob/master/django/utils/_os.py#L24-L32
I'm not sure tho, because the method must return at least None
, therefore I don't see how the attribute error is being raised.
Change History (7)
comment:1 by , 9 years ago
Resolution: | → worksforme |
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Status: | new → closed |
comment:2 by , 9 years ago
Let me try to convince you then. I just changed it to the documented default_storage
helper, which is nothing other than DefaultStorage()
.
I also just added a little test, that tests only storage.location. That works, that doesn't mean there isn't a problem tho.
See the tests don't even execute the case with a default storage.
It uses the FieldFile
's storage.
Besides all that, I don't do any wizardry with the storages, nor in the settings. It must strike you, that there is a different behavior on python 2.7 and 3.*
comment:3 by , 9 years ago
Resolution: | worksforme → fixed |
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I found the bug. It's the lazy object implementation of the default storage. It doesn't work in python 2 using multiprocessing.
This little snippet allows to produce the error.
def has_location(storage): return hasattr(storage, 'location') def test_multiprocessing_lazy_objects(image_upload_file): SimpleModel.objects.create(image=image_upload_file) obj = SimpleModel.objects.last() storage = obj.image.storage p = Pool(2) assert all(p.map(has_location, [default_storage, storage]))
comment:4 by , 9 years ago
Resolution: | fixed |
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Status: | closed → new |
comment:5 by , 9 years ago
Description: | modified (diff) |
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Summary: | AttributeError: 'FileSystemStorage' object has no attribute 'location' → LazyObject doesn't support multiprocessing on Python 2 |
Triage Stage: | Unreviewed → Accepted |
comment:6 by , 8 years ago
Keywords: | py2 added |
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comment:7 by , 8 years ago
Resolution: | → wontfix |
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Status: | new → closed |
Doesn't look like anyone will tackle this before we drop Python 2.
Creating a storage instance as a function parameter ((
DefaultStorage()
for render_variations) looks a bit suspicious to me. I'm not convinced the problem is on Django's side.