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Add _testcapi.stack_pointer() to measure the C stack consumption #75049

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vstinner opened this issue Jul 6, 2017 · 6 comments
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Add _testcapi.stack_pointer() to measure the C stack consumption #75049

vstinner opened this issue Jul 6, 2017 · 6 comments
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3.7 (EOL) end of life

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@vstinner
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vstinner commented Jul 6, 2017

BPO 30866
Nosy @vstinner, @serhiy-storchaka
PRs
  • [2.7] bpo-30866: Add _testcapi.stack_pointer() #2600
  • bpo-30866: Add _testcapi.stack_pointer() #2601
  • [3.6] bpo-30866: Add _testcapi.stack_pointer() #2602
  • [3.5] bpo-30866: Add _testcapi.stack_pointer() #2603
    		•
    Files
  • stack_overflow-3.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 2017-09-15.16:38:44.368>
created_at = <Date 2017-07-06.10:51:19.887>
labels = ['3.7']
title = 'Add _testcapi.stack_pointer() to measure the C stack consumption'
updated_at = <Date 2017-09-15.16:38:44.367>
user = 'https://github.com/vstinner'

    bugs.python.org fields:

    activity = <Date 2017-09-15.16:38:44.367>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2017-09-15.16:38:44.368>
closer = 'vstinner'
components = []
creation = <Date 2017-07-06.10:51:19.887>
creator = 'vstinner'
dependencies = []
files = ['46992']
hgrepos = []
issue_num = 30866
keywords = []
message_count = 6.0
messages = ['297822', '297824', '297826', '297829', '298060', '302271']
nosy_count = 2.0
nosy_names = ['vstinner', 'serhiy.storchaka']
pr_nums = ['2600', '2601', '2602', '2603']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue30866'
versions = ['Python 3.7']
    @vstinner
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    vstinner commented Jul 6, 2017

    In issues bpo-28870, bpo-29227, bpo-29233 and bpo-29234, I worked on reducing the C stack consumption. I now would to add the _testcapi.stack_pointer() that I used to be able to easily measure the stack consumption.

    Try for example attached stack_overflow-3.py to measure the maximum number of C calls before a C stack overflow. The script also computes the average stack usage per C call for a specific kind of C call.

    @vstinner vstinner added the 3.7 (EOL) end of life label Jul 6, 2017
    @serhiy-storchaka
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    Usually we first merge a patch in master and after that cherry-pick it to other branches.

    @vstinner
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    vstinner commented Jul 6, 2017

    Usually we first merge a patch in master and after that cherry-pick it to other branches.

    Right. But in this case, I needed the patch for each branch, to run the test on all branches to write a blog post :-) Here are results (blog post spoiler!):

    Table showing the C stack consumption in bytes, and the difference compared to
    Python 3.5 (last release before I started working on FASTCALL):

    ==================== ================ ===== ================ ================
    Function 2.7 3.5 3.6 3.7
    ==================== ================ ===== ================ ================
    test_python_call 1,360 (+352) 1,008 1,120 (+112) 960 (-48)
    test_python_getitem 1,408 (+288) 1,120 1,168 (+48) 880 (-240)
    test_python_iterator 1,424 (+192) 1,232 1,200 (-32) 1,024 (-208)
    Total 4,192 (+832) 3,360 3,488 (+128) 2,864 (-496)
    ==================== ================ ===== ================ ================

    Table showing the number of function calls before a stack overflow,
    and the difference compared to Python 3.5:

    ==================== =================== ====== =================== ===================
    Function 2.7 3.5 3.6 3.7
    ==================== =================== ====== =================== ===================
    test_python_call 6,161 (-2,153) 8,314 7,482 (-832) 8,729 (+415)
    test_python_getitem 5,951 (-1,531) 7,482 7,174 (-308) 9,522 (+2,040)
    test_python_iterator 5,885 (-916) 6,801 6,983 (+182) 8,184 (+1,383)
    Total 17,997 (-4600) 22,597 21,639 (-958) 26,435 (+3,838)
    ==================== =================== ====== =================== ===================

    @vstinner
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    vstinner commented Jul 6, 2017

    I just published my blog post: "My contributions to CPython during 2017 Q1"
    https://haypo.github.io/contrib-cpython-2017q1.html

    See the "Stack consumption" section.

    @vstinner
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    New changeset 64fa449 by Victor Stinner in branch 'master':
    bpo-30866: Add _testcapi.stack_pointer() (bpo-2601)
    64fa449

    @vstinner
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    I added the function to the master branch.

    I changed my mind. I now consider that the function is no needed in other branches. It can be added manually if someone needs it.

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
    @vstinner vstinner mentioned this issue Aug 22, 2023
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