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Add a function to get GC statistics #60555

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pitrou opened this issue Oct 28, 2012 · 11 comments
Closed

Add a function to get GC statistics #60555

pitrou opened this issue Oct 28, 2012 · 11 comments
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stdlib Python modules in the Lib dir type-feature A feature request or enhancement

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@pitrou
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pitrou commented Oct 28, 2012

BPO 16351
Nosy @gpshead, @jcea, @pitrou, @tiran, @benjaminp, @serhiy-storchaka
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  • gc_get_stats.patch
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    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 2012-10-30.21:47:16.794>
created_at = <Date 2012-10-28.17:30:20.783>
labels = ['type-feature', 'library']
title = 'Add a function to get GC statistics'
updated_at = <Date 2013-12-26.20:12:54.178>
user = 'https://github.com/pitrou'

    bugs.python.org fields:

    activity = <Date 2013-12-26.20:12:54.178>
actor = 'python-dev'
assignee = 'none'
closed = True
closed_date = <Date 2012-10-30.21:47:16.794>
closer = 'pitrou'
components = ['Library (Lib)']
creation = <Date 2012-10-28.17:30:20.783>
creator = 'pitrou'
dependencies = []
files = ['27768']
hgrepos = []
issue_num = 16351
keywords = ['patch']
message_count = 11.0
messages = ['174060', '174062', '174063', '174067', '174068', '174069', '174070', '174230', '174231', '174236', '206958']
nosy_count = 7.0
nosy_names = ['gregory.p.smith', 'jcea', 'pitrou', 'christian.heimes', 'benjamin.peterson', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'low'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue16351'
versions = ['Python 3.4']
    @pitrou
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    pitrou commented Oct 28, 2012

    This patch adds a function named gc.get_stats() which returns a list of dictionaries containing per-generation statistics:

    >>> import pprint, gc
>>> pprint.pprint(gc.get_stats())
[{'collected': 0, 'collections': 12, 'uncollectable': 0},
 {'collected': 0, 'collections': 1, 'uncollectable': 0},
 {'collected': 0, 'collections': 0, 'uncollectable': 0}]

    @pitrou pitrou added stdlib Python modules in the Lib dir type-feature A feature request or enhancement labels Oct 28, 2012
    @tiran
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    tiran commented Oct 28, 2012

    What are the possible performance implications of the statistics?

    @pitrou
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    pitrou commented Oct 28, 2012

    You mean negative implications? None :-)

    @serhiy-storchaka
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    Why dictionaries and not struct sequences?

    @serhiy-storchaka
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    Oh, I understand. GC callbacks receive a dict.

    For avoid confusion with gc.DEBUG_STATS and to conform with callbacks argument name, may be better to name this function as gc.get_infos([generation])?

    @serhiy-storchaka
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    I.e. gc.get_info([generation]). Returns the info for specified generation or total if the parameter omitted.

    @pitrou
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    pitrou commented Oct 28, 2012

    Why dictionaries and not struct sequences?

    Because it's much simpler like that.

    For avoid confusion with gc.DEBUG_STATS and to conform with callbacks
    argument name, may be better to name this function as
    gc.get_infos([generation])?

    Well, this is really about statistics, not general information.
    Furthermore, it is not related to the callbacks functionality.
    As for the generation parameter, I don't think it's useful: the result
    list is only 3 elements long.

    @python-dev
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    python-dev mannequin commented Oct 30, 2012

    New changeset 43d87cdf9457 by Antoine Pitrou in branch 'default':
    Issue bpo-16351: New function gc.get_stats() returns per-generation collection statistics.
    http://hg.python.org/cpython/rev/43d87cdf9457

    @pitrou
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    pitrou commented Oct 30, 2012

    Now committed.

    @pitrou pitrou closed this as completed Oct 30, 2012
    @serhiy-storchaka
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    Because it's much simpler like that.

    Well, I wrote a patch with structure sequences, it is really much more expansive.

    I have some comments.

    1. You can allocate list of NUM_GENERATIONS elements and then use PyList_SET_ITEM(result, i, stat). This is 4 lines shorter.

    2. And may be return the tuple? get_count() and get_threshold() return tuples.

    3. You forgot to add get_stats() to the module docstring.

    @python-dev
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    python-dev mannequin commented Dec 26, 2013

    New changeset 17bd04fbf3d3 by R David Murray in branch 'default':
    whatsnew for gc.get_stats, plus doc tweaks.
    http://hg.python.org/cpython/rev/17bd04fbf3d3

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