Re: PyWart: The problem with "print"

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Date	2013-06-03 13:37 +1000
Subject	Re: PyWart: The problem with "print"
From	Tim Delaney <timothy.c.delaney@gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.2577.1370230651.3114.python-list@python.org> (permalink)

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On 3 June 2013 13:23, Jason Swails <jason.swails@gmail.com> wrote:

> Yea, I've only run into Heisenbugs with Fortran or C/C++.  Every time I've
> seen one it's been due to an uninitialized variable somewhere -- something
> valgrind is quite good at pinpointing.  (And yes, a good portion of our
> code is -still- in Fortran -- but at least it's F90+ :).
>

With the increase in use of higher-level languages, these days Heisenbugs
most often appear with multithreaded code that doesn't properly protect
critical sections, but as you say, with lower-level languages uninitialised
memory is a common source of them.

I had a fun one once (in C++, but could have happened in any language)
where a semaphore was being acquired twice on the one thread. There were 10
semaphore slots available, and very occasionally the timings would result
in one of the threads deadlocking. Fortunately, by reducing to a single
thread + single semaphore slot I was able to turn it from a Heisenbug to a
100% replicable bug.

Tim Delaney

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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