[Python-Dev] PEP 418 is too divisive and confusing and should be postponed

PJ Eby pje at telecommunity.com
Thu Apr 5 18:48:13 CEST 2012

On Thu, Apr 5, 2012 at 6:34 AM, Victor Stinner <victor.stinner at gmail.com>wrote:

> 2012/4/5 PJ Eby <pje at telecommunity.com>:
> >> More details why it's hard to define such function and why I dropped
> >> it from the PEP.
> >>
> >> If someone wants to propose again such function ("monotonic or
> >> fallback to system" clock), two issues should be solved:
> >>
> >>  - name of the function
> >>  - description of the function
> >
> > Maybe I missed it, but did anyone ever give a reason why the fallback
> > couldn't be to Steven D'Aprano's monotonic wrapper algorithm over the
> system
> > clock?  (Given a suitable minimum delta.)  That function appeared to me
> to
> > provide a sufficiently monotonic clock for timeout purposes, if nothing
> > else.
> Did you read the following section of the PEP?
> http://www.python.org/dev/peps/pep-0418/#working-around-operating-system-bugs
> Did I miss something? If yes, could you write a patch for the PEP please?

What's missing is that if you're using a monotonic clock for timeouts, then
a monotonically-adjusted system clock can do that, subject to the polling
frequency -- it does not break just because the system clock is set
backwards; it simply loses time proportional to the frequency with which it
is polled.

For timeout purposes in a single process, such a clock is useful.  It just
isn't suitable for benchmarks, or for interprocess coordination.
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