Py 3 slower than Py 2. Towers of Hanoi implementation

Udyant Wig udyantw at gmail.com
Fri Jun 26 19:16:40 CEST 2009


On Jun 26, 8:01 pm, Paul Moore <p.f.mo... at gmail.com> wrote:
> 2009/6/26 Udyant Wig <udya... at gmail.com>:
>
>
>
>
>
> > I implemented this ->http://www.apl.jhu.edu/~hall/lisp/Hanoi.lispin
> > both flavors of Python: 2.6.2 and 3.0.1 (CPython)
>
> > The code:
> > #!/usr/bin/env python
> > def remaining_peg (peg1, peg2):
> >        return (6 - peg1 - peg2)
>
> > def hanoi (num_discs, start, end):
> >        if (1 == num_discs):
> >                print "Top of peg {0} to peg {1}".format(start,end) # used print()
> > for Py 3.0.1
>
> >        else:
> >                hanoi ((num_discs - 1), start, (remaining_peg (start, end)))
> >                hanoi (1, start, end)
> >                hanoi ((num_discs - 1), (remaining_peg (start, end)), end)
>
> > hanoi(20,2,3)
>
> > The times:            real          usr          sys
> > Python 2.6.2       7.994s    3.336s   3.296s
> > Python 3.0.1       55.302s  38.024s 5.876s
>
> > What happened to Python?
>
> I/O in Python 3.0 is known to be slow, because the bulk of the
> implementation is in Python (rather than C). Python 3.1 addresses
> this. Here are some tests of 2.6.1 vs 3.1rc2. The first tests have the
> print commented out, the second are with the print, redirected to the
> null device. The tests are on a pretty slow Windows XP SP2 laptop.
>
> >timer & \Apps\Python26\python.exe hanoi.py & timer
>
> Timer 1 on: 15:54:53
> Timer 1 off: 15:54:57  Elapsed: 0:00:03.88
>
> >timer & \Apps\Python31\python.exe hanoi.py & timer
>
> Timer 1 on: 15:57:05
> Timer 1 off: 15:57:09  Elapsed: 0:00:03.67
>
> >timer & (\Apps\Python26\python.exe hanoi.py >nul) & timer
>
> Timer 1 on: 15:57:44
> Timer 1 off: 15:58:14  Elapsed: 0:00:29.91
>
> >timer & (\Apps\Python31\python.exe hanoi.py >nul) & timer
>
> Timer 1 on: 15:58:38
> Timer 1 off: 15:59:09  Elapsed: 0:00:30.63
>
> Nothing much in it.
>
> Paul.

Thank you for clearing that up.



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