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Add time.monotonic() function #58054

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vstinner opened this issue Jan 24, 2012 · 11 comments
Closed

Add time.monotonic() function #58054

vstinner opened this issue Jan 24, 2012 · 11 comments
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type-feature A feature request or enhancement

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@vstinner
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BPO 13846
Nosy @terryjreedy, @abalkin, @pitrou, @vstinner, @giampaolo, @ned-deily, @merwok, @bitdancer
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  • monotonic.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 2012-02-07.22:30:30.812>
created_at = <Date 2012-01-24.00:22:29.067>
labels = ['type-feature']
title = 'Add time.monotonic() function'
updated_at = <Date 2012-02-23.23:11:18.533>
user = 'https://github.com/vstinner'

    bugs.python.org fields:

    activity = <Date 2012-02-23.23:11:18.533>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2012-02-07.22:30:30.812>
closer = 'vstinner'
components = []
creation = <Date 2012-01-24.00:22:29.067>
creator = 'vstinner'
dependencies = []
files = ['24307']
hgrepos = []
issue_num = 13846
keywords = ['patch']
message_count = 11.0
messages = ['151868', '152138', '152280', '152505', '152506', '152514', '152816', '152860', '153774', '154096', '154097']
nosy_count = 10.0
nosy_names = ['terry.reedy', 'belopolsky', 'pitrou', 'vstinner', 'giampaolo.rodola', 'ned.deily', 'eric.araujo', 'r.david.murray', 'rosslagerwall', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'patch review'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue13846'
versions = ['Python 3.3']
    @vstinner
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    After time.wallclock() (issue bpo-10278), let add a time.monotomic() function. It is similar to time.wallclock() (try to get the most accurate clock) but is not available if the system doesn't provide a monotonic clock. It may also fail at runtime if Python cannot find a monotonic clock, whereas time.clock() and time.wallclock() fallback on a wallclock which may go backward on NTP adjust.

    The documentation of the patch should be improved :-)

    wallclock() tests may be simplified or dropped because they may fail on NTP adjust.

    @terryjreedy
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    Do we actually yet another function, or could this be covered by adding a parameter such as monotonic=False, perhaps to wallclock().

    @terryjreedy terryjreedy added the type-feature A feature request or enhancement label Jan 27, 2012
    @vstinner
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    Do we actually yet another function, or could this be covered by adding a parameter such as monotonic=False, perhaps to wallclock().

    A monotonic is a different clock, it would be surprising that an
    argument uses another clock.

    @merwok
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    merwok commented Feb 3, 2012

    I don’t understand why this new function would be useful. Time-related modules in Python are already complicated.

    @bitdancer
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    If you are trying to time something (an interval), having the time go backward can really screw up your data. And that *will* happen on a system that is running NTP (or even just resets its time). monotonic clocks were introduced at the OS level for a reason, and it seems reasonable for Python to expose them (when the are available) like it does other system resources.

    @merwok
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    merwok commented Feb 3, 2012

    Thanks, now I see the usefulness.

    @python-dev
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    Mannequin

    python-dev mannequin commented Feb 7, 2012

    New changeset 376ce937823c by Victor Stinner in branch 'default':
    Issue bpo-13846: Add time.monotonic(), monotonic clock.
    http://hg.python.org/cpython/rev/376ce937823c

    @vstinner vstinner closed this as completed Feb 7, 2012
    @merwok
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    merwok commented Feb 8, 2012

    Victor, I think the doc doesn’t say why the function is useful for people like me who don’t already know it. David’s explanation could be reused.

    @pitrou
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    pitrou commented Feb 20, 2012

    Boost has a monotonic time implementation (steady_clock) for OS X:
    http://svn.boost.org/svn/boost/trunk/boost/chrono/detail/inlined/mac/chrono.hpp

    @python-dev
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    python-dev mannequin commented Feb 23, 2012

    New changeset 50b1f2d07011 by Victor Stinner in branch 'default':
    Issue bpo-13846: Enhance time.monotonic() documentation
    http://hg.python.org/cpython/rev/50b1f2d07011

    @vstinner
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    Boost has a monotonic time implementation (steady_clock) for OS X

    I opened a new issue for Mac OS X: bpo-14104.

    --

    @Éric: I enhanced the doc. Feel free to complete or rewrite it if you have better information about such clocks.

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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    @vstinner @bitdancer @merwok @pitrou @terryjreedy