Performance issue using isspace() in extension module on Windows

[Clemens]

BPO	41601
Nosy	@pfmoore, @tjguk, @merwok, @zware, @zooba, @dstufft
Files	isspace_ext.cpp setup.py test.py

^{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 2021-02-03.18:05:43.273>
created_at = <Date 2020-08-20.16:30:59.139>
labels = ['3.8', '3.9', 'performance', '3.7', 'library', 'OS-windows']
title = 'Performance issue using isspace() in extension module on Windows'
updated_at = <Date 2021-02-03.18:05:43.273>
user = 'https://bugs.python.org/Clemens'

bugs.python.org fields:

activity = <Date 2021-02-03.18:05:43.273>
actor = 'steve.dower'
assignee = 'none'
closed = True
closed_date = <Date 2021-02-03.18:05:43.273>
closer = 'steve.dower'
components = ['Distutils', 'Windows']
creation = <Date 2020-08-20.16:30:59.139>
creator = 'Clemens'
dependencies = []
files = ['49411', '49412', '49413']
hgrepos = []
issue_num = 41601
keywords = []
message_count = 2.0
messages = ['375722', '386242']
nosy_count = 7.0
nosy_names = ['paul.moore', 'tim.golden', 'eric.araujo', 'zach.ware', 'steve.dower', 'dstufft', 'Clemens']
pr_nums = []
priority = 'normal'
resolution = 'out of date'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue41601'
versions = ['Python 3.7', 'Python 3.8', 'Python 3.9']

[Clemens]

Function isspace() is significantly slower in extension modules in Python 3.7 or later than in Python 3.6 on Windows 10.

Python 3.6:

python test.py
Locale: C
Set locale: C
Locale: C
Duration: 0.19718074798583984

Python 3.7:

python test.py
Locale: C
Set locale: C
Locale: C
Duration: 2.9086477756500244

Python 3.8:

python test.py
Locale: LC_COLLATE=C;LC_CTYPE=English_Germany.1252;LC_MONETARY=C;LC_NUMERIC=C;LC_TIME=C
Set locale: C
Locale: C
Duration: 2.99224853515625

Python 3.9.0a5:

python test.py
Locale: LC_COLLATE=C;LC_CTYPE=English_Germany.1252;LC_MONETARY=C;LC_NUMERIC=C;LC_TIME=C
Set locale: C
Locale: C
Duration: 2.90370512008667

Building the extension module:

python setup.py build_ext

A similar issue already exists, but I am not sure if it is the same problem since the suggested solution is about embedding Python rather then extending it: https://bugs.python.org/issue35195

[zooba]

Distutils is now deprecated (see PEP-632) and all tagged issues are being closed. From now until removal, only release blocking issues will be considered for distutils.

If this issue does not relate to distutils, please remove the component and reopen it. If you believe it still requires a fix, most likely the issue should be re-reported at https://github.com/pypa/setuptools