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cpu_count() unreliable on Windows #67226
Description
| BPO | 23037 |
|---|---|
| Nosy | @vstinner, @tjguk, @mark-summerfield, @zware, @zooba |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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GitHub fields:
assignee = None
closed_at = <Date 2014-12-12.13:13:57.454>
created_at = <Date 2014-12-12.12:36:11.806>
labels = ['type-bug', 'library', 'OS-windows']
title = 'cpu_count() unreliable on Windows'
updated_at = <Date 2014-12-12.13:13:57.452>
user = 'https://github.com/mark-summerfield'bugs.python.org fields:
activity = <Date 2014-12-12.13:13:57.452>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2014-12-12.13:13:57.454>
closer = 'vstinner'
components = ['Library (Lib)', 'Windows']
creation = <Date 2014-12-12.12:36:11.806>
creator = 'mark'
dependencies = []
files = []
hgrepos = []
issue_num = 23037
keywords = []
message_count = 2.0
messages = ['232540', '232544']
nosy_count = 5.0
nosy_names = ['vstinner', 'tim.golden', 'mark', 'zach.ware', 'steve.dower']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue23037'
versions = ['Python 2.7', 'Python 3.2', 'Python 3.3', 'Python 3.4']
Activity
mark-summerfield commentedon Dec 12, 2014
In message
http://bugs.python.org/issue17914#msg188626
Victor Stenner says
"On Windows, GetSystemInfo() is called instead of reading an environment variable. I suppose that this function is more reliable."
From my reading, and based on feedback from one of my customers, I believe he is correct and that GetSystemInfo() ought to be used on Windows. (It is available in pywin32 win32api.)
vstinner commentedon Dec 12, 2014
The code getting the number of processors on Windows is different between the multiprocessing (Python 3.3) and os (Python 3.5) modules.
multiprocessing (old code):
os (new code):
os.cpu_count() is already implemented with GetSystemInfo() in Python 3.5, so this issue can be closed. Thanks for the reminder Mark, it was useful to double check.
If you want to take a look at the source code:
https://hg.python.org/cpython/file/35b7dde7fd53/Modules/posixmodule.c#l16064