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Re: time.monotonic() roll over

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Date Fri, 5 Dec 2014 03:12:48 +1100
Subject Re: time.monotonic() roll over
From Chris Angelico <rosuav@gmail.com>
Cc Python <python-list@python.org>
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On Fri, Dec 5, 2014 at 3:05 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
> On Dec 4, 2014 8:56 AM, "Marko Rauhamaa" <marko@pacujo.net> wrote:
>>
>> "ast" <nomail@invalid.com>:
>>
>> > Does any body know when time.monotonic() rolls over ?
>>
>> Never, according to the documentation you linked.
>>
>> Admittedly, the documentation confuses the reader by chatting about some
>> irrelevant internal Windows details.
>
> Not entirely irrelevant. The implication is that if you go more than 49 days
> without calling the function on old Windows systems, rollovers could be
> missed, which is good to know about. The result would still be monotonic,
> but it wouldn't accurately reflect the time elapsed.

I don't know for sure about the newer Windowses, but I believe they
use a 64-bit counter instead of the 32-bit one used in previous
versions, so even if they do roll over, there'll be a much MUCH longer
time scale involved. Even if it stores time in nanoseconds, a 64-bit
counter would allow for hundreds of years between rollovers, which is
reasonably safe - much better than the month-and-a-bit of older ones,
which is shorter than quite a lot of my programs' uptimes. Hence the
lack of information about them; you don't have to worry. (Likewise on
Unix-derived systems, I believe, and for the same reason.)

ChrisA

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Thread

time.monotonic() roll over "ast" <nomail@invalid.com> - 2014-12-04 16:25 +0100
  Re: time.monotonic() roll over Marko Rauhamaa <marko@pacujo.net> - 2014-12-04 17:50 +0200
    Re: time.monotonic() roll over Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-04 09:05 -0700
      Re: time.monotonic() roll over Marko Rauhamaa <marko@pacujo.net> - 2014-12-04 18:21 +0200
        Re: time.monotonic() roll over Chris Angelico <rosuav@gmail.com> - 2014-12-05 03:27 +1100
          Re: time.monotonic() roll over Marko Rauhamaa <marko@pacujo.net> - 2014-12-04 20:09 +0200
            Re: time.monotonic() roll over Chris Angelico <rosuav@gmail.com> - 2014-12-05 05:29 +1100
              Re: time.monotonic() roll over Marko Rauhamaa <marko@pacujo.net> - 2014-12-04 20:44 +0200
                Re: time.monotonic() roll over Chris Angelico <rosuav@gmail.com> - 2014-12-05 07:02 +1100
            Re: time.monotonic() roll over Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-04 12:29 -0700
            Re: time.monotonic() roll over Akira Li <4kir4.1i@gmail.com> - 2014-12-04 23:24 +0300
            Re: time.monotonic() roll over Chris Angelico <rosuav@gmail.com> - 2014-12-05 07:33 +1100
              Re: time.monotonic() roll over Marko Rauhamaa <marko@pacujo.net> - 2014-12-04 22:51 +0200
            Re: time.monotonic() roll over Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-04 15:17 -0700
              Re: time.monotonic() roll over Marko Rauhamaa <marko@pacujo.net> - 2014-12-05 00:44 +0200
                Re: time.monotonic() roll over Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-05 10:04 -0700
                Re: time.monotonic() roll over Marko Rauhamaa <marko@pacujo.net> - 2014-12-05 20:48 +0200
            Re: time.monotonic() roll over Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-05 11:39 +1100
              Re: time.monotonic() roll over Dave Angel <davea@davea.name> - 2014-12-04 20:21 -0500
                Re: time.monotonic() roll over Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-05 13:54 +1100
                Re: time.monotonic() roll over Dave Angel <davea@davea.name> - 2014-12-05 00:29 -0500
                Re: time.monotonic() roll over Lele Gaifax <lele@metapensiero.it> - 2014-12-05 08:56 +0100
                Re: time.monotonic() roll over Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-05 21:09 +1100
                Re: time.monotonic() roll over Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-12-05 12:12 -0500
              Re: time.monotonic() roll over Marko Rauhamaa <marko@pacujo.net> - 2014-12-05 08:17 +0200
                Re: time.monotonic() roll over Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-12-05 12:31 -0500
              Re: time.monotonic() roll over Akira Li <4kir4.1i@gmail.com> - 2014-12-05 12:48 +0300
    Re: time.monotonic() roll over Chris Angelico <rosuav@gmail.com> - 2014-12-05 03:12 +1100
    Re: time.monotonic() roll over random832@fastmail.us - 2014-12-04 11:51 -0500
  Re: time.monotonic() roll over Nobody <nobody@nowhere.invalid> - 2014-12-05 00:54 +0000

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