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Refactor duplicate code calculating digit's bit length #72807

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adrian17 mannequin opened this issue Nov 5, 2016 · 5 comments
Closed

Refactor duplicate code calculating digit's bit length #72807

adrian17 mannequin opened this issue Nov 5, 2016 · 5 comments
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3.7 (EOL) end of life interpreter-core (Objects, Python, Grammar, and Parser dirs) performance Performance or resource usage

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@adrian17
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adrian17 mannequin commented Nov 5, 2016

BPO 28621
Nosy @mdickinson, @serhiy-storchaka, @adrian17
PRs
  • [Do Not Merge] Convert Misc/NEWS so that it is managed by towncrier #552
    		•
    Files
  • bit_length.patch
    		•

    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 2016-11-08.18:36:05.507>
created_at = <Date 2016-11-05.19:37:28.766>
labels = ['interpreter-core', '3.7', 'performance']
title = "Refactor duplicate code calculating digit's bit length"
updated_at = <Date 2017-03-31.16:36:09.041>
user = 'https://github.com/adrian17'

    bugs.python.org fields:

    activity = <Date 2017-03-31.16:36:09.041>
actor = 'dstufft'
assignee = 'none'
closed = True
closed_date = <Date 2016-11-08.18:36:05.507>
closer = 'serhiy.storchaka'
components = ['Interpreter Core']
creation = <Date 2016-11-05.19:37:28.766>
creator = 'Adrian Wielgosik'
dependencies = []
files = ['45367']
hgrepos = []
issue_num = 28621
keywords = ['patch']
message_count = 5.0
messages = ['280123', '280131', '280240', '280331', '280333']
nosy_count = 4.0
nosy_names = ['mark.dickinson', 'python-dev', 'serhiy.storchaka', 'Adrian Wielgosik']
pr_nums = ['552']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue28621'
versions = ['Python 3.7']
    @adrian17
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    adrian17 mannequin commented Nov 5, 2016

    The attached patch uses an existing function bits_in_digit() in two other functions:

    • in long_bit_length() - it already had identical logic
    • in _PyLong_NumBits() - it used a naive, slower way of calculating bit length, so as an added bonus the patch speeds it up a bit. It's visible in float-long comparison microbenchmark:
    $ ./old -m timeit "1 == 1.0"
5000000 loops, best of 5: 55 nsec per loop

$ ./new -m timeit "1 == 1.0"
5000000 loops, best of 5: 52.3 nsec per loop

$ ./old -m timeit "12345678 == 12345678.0"
5000000 loops, best of 5: 70.4 nsec per loop

$ ./new -m timeit "12345678 == 12345678.0"
5000000 loops, best of 5: 53.5 nsec per loop

    @adrian17 adrian17 mannequin added 3.7 (EOL) end of life interpreter-core (Objects, Python, Grammar, and Parser dirs) performance Performance or resource usage labels Nov 5, 2016
    @serhiy-storchaka
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    LGTM.

    @mdickinson
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    LGTM, too.

    @python-dev
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    python-dev mannequin commented Nov 8, 2016

    New changeset 1940b72b0a02 by Serhiy Storchaka in branch 'default':
    Issue bpo-28621: Sped up converting int to float by reusing faster bits counting
    https://hg.python.org/cpython/rev/1940b72b0a02

    @serhiy-storchaka
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    Thank you Adrian for your contribution.

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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