Re: PyWart: The problem with "print"

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Date	2013-06-03 15:09 -0400
Subject	Re: PyWart: The problem with "print"
From	Jason Swails <jason.swails@gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.2603.1370286598.3114.python-list@python.org> (permalink)

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On Mon, Jun 3, 2013 at 1:12 PM, Ian Kelly <ian.g.kelly@gmail.com> wrote:

> On Sun, Jun 2, 2013 at 6:16 PM, Jason Swails <jason.swails@gmail.com>
> wrote:
> > I'm actually with RR in terms of eliminating the overhead involved with
> > 'dead' function calls, since there are instances when optimizing in
> Python
> > is desirable.  I actually recently adjusted one of my own scripts to
> > eliminate branching and improve data layout to achieve a 1000-fold
> > improvement in efficiency (~45 minutes to 0.42 s. for one example) ---
> all
> > in pure Python.  The first approach was unacceptable, the second is fine.
> > For comparison, if I add a 'deactivated' debugprint call into the inner
> loop
> > (executed 243K times in this particular test), then the time of the
> > double-loop step that I optimized takes 0.73 seconds (nearly doubling the
> > duration of the whole step).
>
> It seems to me that your problem here wasn't that the time needed for
> the deactivated debugprint was too great. Your problem was that a
> debugprint that executes 243K times in 0.73 seconds is going to
> generate far too much output to be useful, and it had no business
> being there in the first place.  *Reasonably* placed debugprints are
> generally not going to be a significant time-sink for the application
> when disabled.

Well in 'debug' mode I wouldn't use an example that executed the loop 200K
times -- I'd find one that executed a manageable couple dozen, maybe.
 When 'disabled,' the print statement won't do anything except consume
clock cycles and potentially displace useful cache (the latter being the
more harmful, since most applications are bound by the memory bus).  It's
better to eliminate this dead call when you're not in 'debugging' mode.
 (When active, it certainly would've taken more than 0.73
seconds) Admittedly such loops should be tight enough that debugging
statements inside the inner loop are generally unnecessary, but perhaps not
always.

But unlike RR, who suggests some elaborate interpreter-wide, ambiguous
ignore-rule to squash out all of these functions, I'm simply suggesting
that sometimes it's worth commenting-out debug print calls instead of 'just
leaving them there because you won't notice the cost' :).

> The easiest way to eliminate these 'dead' calls is to simply comment-out
> the
> > print call, but I would be quite upset if the interpreter tried to
> outsmart
> > me and do it automagically as RR seems to be suggesting.
>
> Indeed, the print function is for general output, not specifically for
> debugging.  If you have the global print deactivation that RR is
> suggesting, then what you have is no longer a print function, but a
> misnamed debug function.
>

Exactly.  I was just trying to make the point that it is -occasionally-
worth spending the time to comment-out certain debug calls rather than
leaving 'dead' function calls in certain places.

All the best,
Jason

-- 
Jason M. Swails
Quantum Theory Project,
University of Florida
Ph.D. Candidate
352-392-4032

Thread

PyWart: The problem with "print" Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-02 10:04 -0700
  Re: PyWart: The problem with "print" Chris Angelico <rosuav@gmail.com> - 2013-06-03 03:20 +1000
    Re: PyWart: The problem with "print" Dan Sommers <dan@tombstonezero.net> - 2013-06-02 17:49 +0000
      Re: PyWart: The problem with "print" Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-02 11:18 -0700
        Re: PyWart: The problem with "print" Ned Batchelder <ned@nedbatchelder.com> - 2013-06-02 16:45 -0400
        Re: PyWart: The problem with "print" Michael Torrie <torriem@gmail.com> - 2013-06-02 23:49 -0600
        Re: PyWart: The problem with "print" Chris Angelico <rosuav@gmail.com> - 2013-06-03 17:17 +1000
          Re: PyWart: The problem with "print" Alister <alister.ware@ntlworld.com> - 2013-06-03 08:01 +0000
    Re: PyWart: The problem with "print" Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-02 11:09 -0700
      Re: PyWart: The problem with "print" Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-02 19:03 +0000
      Re: PyWart: The problem with "print" Chris Angelico <rosuav@gmail.com> - 2013-06-03 06:21 +1000
      Re: PyWart: The problem with "print" jmfauth <wxjmfauth@gmail.com> - 2013-06-04 05:23 -0700
        Re: PyWart: The problem with "print" rusi <rustompmody@gmail.com> - 2013-06-04 06:29 -0700
          Re: PyWart: The problem with "print" Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-04 14:35 +0100
        Re: PyWart: The problem with "print" Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-05 05:03 +0000
  Re: PyWart: The problem with "print" Andrew Berg <robotsondrugs@gmail.com> - 2013-06-02 12:30 -0500
  Re: PyWart: The problem with "print" Chris Angelico <rosuav@gmail.com> - 2013-06-03 03:34 +1000
  Re: PyWart: The problem with "print" Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-02 18:58 +0000
    Re: PyWart: The problem with "print" Chris Angelico <rosuav@gmail.com> - 2013-06-03 06:28 +1000
    Re: PyWart: The problem with "print" Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-03 18:37 -0700
      Re: PyWart: The problem with "print" Vito De Tullio <vito.detullio@gmail.com> - 2013-06-04 05:16 +0200
        Re: PyWart: The problem with "print" Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-03 20:53 -0700
        Re: PyWart: The problem with "print" Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-04 04:30 +0000
      Bools and explicitness [was Re: PyWart: The problem with "print"] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-04 05:39 +0000
        Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-04 08:44 -0700
          Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-05 02:00 +1000
            Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-04 09:19 -0700
              Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-05 02:27 +1000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-05 05:28 +0000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] alex23 <wuwei23@gmail.com> - 2013-06-04 22:31 -0700
              Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Ned Batchelder <ned@nedbatchelder.com> - 2013-06-04 13:25 -0400
          Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-04 09:09 -0700
            Re: Bools and explicitness [was Re: PyWart: The problem with "print"] alex23 <wuwei23@gmail.com> - 2013-06-04 18:31 -0700
          Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Fábio Santos <fabiosantosart@gmail.com> - 2013-06-04 17:10 +0100
          Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Jason Swails <jason.swails@gmail.com> - 2013-06-04 13:32 -0400
          Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-04 11:42 -0600
            Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-04 16:21 -0700
              Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-05 00:37 +0100
              Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Michael Torrie <torriem@gmail.com> - 2013-06-04 23:28 -0600
          Re: Bools and explicitness [was Re: PyWart: The problem with "print"] "Russ P." <Russ.Paielli@gmail.com> - 2013-06-04 23:11 -0700
            Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-05 17:15 +1000
              Re: Bools and explicitness [was Re: PyWart: The problem with "print"] "Russ P." <Russ.Paielli@gmail.com> - 2013-06-05 00:47 -0700
              Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-06 09:49 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-07 02:59 +1000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Dan Stromberg <drsalists@gmail.com> - 2013-06-06 18:26 -0700
            Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-05 09:59 +0100
              Re: Bools and explicitness [was Re: PyWart: The problem with "print"] "Russ P." <Russ.Paielli@gmail.com> - 2013-06-05 09:15 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-06 02:59 +1000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] "Russ P." <Russ.Paielli@gmail.com> - 2013-06-05 14:59 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-06 01:56 +0000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-06 12:29 +1000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] "Russ P." <Russ.Paielli@gmail.com> - 2013-06-05 21:25 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-06 00:06 -0600
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-06 09:29 +0000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-06 19:45 +1000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Serhiy Storchaka <storchaka@gmail.com> - 2013-06-06 14:12 +0300
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Robert Kern <robert.kern@gmail.com> - 2013-06-06 16:35 +0100
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-07 01:41 +1000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Robert Kern <robert.kern@gmail.com> - 2013-06-06 17:08 +0100
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] rusi <rustompmody@gmail.com> - 2013-06-06 10:27 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Devin Jeanpierre <jeanpierreda@gmail.com> - 2013-06-06 14:44 -0400
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Mark Janssen <dreamingforward@gmail.com> - 2013-06-06 10:59 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] alex23 <wuwei23@gmail.com> - 2013-06-06 17:53 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Mark Janssen <dreamingforward@gmail.com> - 2013-06-06 18:44 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] alex23 <wuwei23@gmail.com> - 2013-06-06 19:03 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Mark Janssen <dreamingforward@gmail.com> - 2013-06-06 22:01 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-07 02:29 +0000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Mark Janssen <dreamingforward@gmail.com> - 2013-06-06 20:14 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] rusi <rustompmody@gmail.com> - 2013-06-06 20:24 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Mark Janssen <dreamingforward@gmail.com> - 2013-06-06 20:30 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] rusi <rustompmody@gmail.com> - 2013-06-06 20:43 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] "Russ P." <Russ.Paielli@gmail.com> - 2013-06-06 11:08 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-06 08:49 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-07 02:00 +1000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Grant Edwards <invalid@invalid.invalid> - 2013-06-06 17:32 +0000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-06 01:37 +0000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-06 11:45 +1000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] rusi <rustompmody@gmail.com> - 2013-06-06 07:09 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-07 01:26 +1000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] rusi <rustompmody@gmail.com> - 2013-06-06 08:36 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Chris Angelico <rosuav@gmail.com> - 2013-06-07 01:46 +1000
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-06 11:03 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-06 11:11 -0700
            Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Terry Jan Reedy <tjreedy@udel.edu> - 2013-06-05 12:10 -0400
            Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Michael Torrie <torriem@gmail.com> - 2013-06-05 17:18 -0600
              Re: Bools and explicitness [was Re: PyWart: The problem with "print"] "Russ P." <Russ.Paielli@gmail.com> - 2013-06-05 16:52 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Michael Torrie <torriem@gmail.com> - 2013-06-05 19:20 -0600
              Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-06 09:24 -0700
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] Devin Jeanpierre <jeanpierreda@gmail.com> - 2013-06-06 12:39 -0400
                Re: Bools and explicitness [was Re: PyWart: The problem with "print"] alex23 <wuwei23@gmail.com> - 2013-06-06 17:55 -0700
      Re: PyWart: The problem with "print" Chris Angelico <rosuav@gmail.com> - 2013-06-04 17:30 +1000
  Re: PyWart: The problem with "print" Jason Swails <jason.swails@gmail.com> - 2013-06-02 20:16 -0400
    Re: PyWart: The problem with "print" Dan Sommers <dan@tombstonezero.net> - 2013-06-03 03:10 +0000
      Re: PyWart: The problem with "print" Jason Swails <jason.swails@gmail.com> - 2013-06-02 23:23 -0400
        Re: PyWart: The problem with "print" Dan Sommers <dan@tombstonezero.net> - 2013-06-03 04:20 +0000
          Re: PyWart: The problem with "print" Robert Kern <robert.kern@gmail.com> - 2013-06-03 11:52 +0100
      Re: PyWart: The problem with "print" Tim Delaney <timothy.c.delaney@gmail.com> - 2013-06-03 13:37 +1000
        Python Heisenbugs?  (was: Re: PyWart: The problem with "print") Dan Sommers <dan@tombstonezero.net> - 2013-06-03 04:34 +0000
          Re: Python Heisenbugs? (was: Re: PyWart: The problem with "print") Chris Angelico <rosuav@gmail.com> - 2013-06-03 15:05 +1000
          Re: Python Heisenbugs? (was: Re: PyWart: The problem with "print") Devin Jeanpierre <jeanpierreda@gmail.com> - 2013-06-03 03:06 -0400
      Re: PyWart: The problem with "print" Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-03 09:49 +0100
      Re: PyWart: The problem with "print" Dave Angel <davea@davea.name> - 2013-06-03 08:56 -0400
  Re: PyWart: The problem with "print" Chris Angelico <rosuav@gmail.com> - 2013-06-03 12:02 +1000
  Re: PyWart: The problem with "print" Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-03 11:12 -0600
  Re: PyWart: The problem with "print" Jason Swails <jason.swails@gmail.com> - 2013-06-03 15:09 -0400
    Re: PyWart: The problem with "print" Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-03 20:31 +0000
      Re: PyWart: The problem with "print" Chris Angelico <rosuav@gmail.com> - 2013-06-04 06:44 +1000
  Re: PyWart: The problem with "print" Jason Swails <jason.swails@gmail.com> - 2013-06-03 15:10 -0400
  Re: PyWart: The problem with "print" Jason Swails <jason.swails@gmail.com> - 2013-06-03 15:11 -0400

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