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

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Add _testcapi.stack_pointer() to measure the C stack consumption#75049
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3.7 (EOL)end of life

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@vstinner
vstinner
opened on 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']

    Activity

    1. vstinner commented on Jul 6, 2017

      @vstinner
      vstinner
      on Jul 6, 2017
      MemberAuthor

      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.

    2. vstinner
      added
      3.7 (EOL)end of life
      on Jul 6, 2017

    3. serhiy-storchaka commented on Jul 6, 2017

      @serhiy-storchaka
      serhiy-storchaka
      on Jul 6, 2017
      Member

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

    4. vstinner commented on Jul 6, 2017

      @vstinner
      vstinner
      on Jul 6, 2017
      MemberAuthor

      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)
      ==================== =================== ====== =================== ===================

    5. vstinner commented on Jul 6, 2017

      @vstinner
      vstinner
      on Jul 6, 2017
      MemberAuthor

      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.

    6. vstinner commented on Jul 10, 2017

      @vstinner
      vstinner
      on Jul 10, 2017
      MemberAuthor

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

    7. vstinner commented on Sep 15, 2017

      @vstinner
      vstinner
      on Sep 15, 2017
      MemberAuthor

      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.

    8. vstinner
      closed this as completedon Sep 15, 2017
    9. ezio-melotti
      transferred this issue fromon Apr 10, 2022
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