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Re: Are threads bad? - was: Future of Pypy?

References (11 earlier) <87h9udb1eq.fsf@jester.gateway.pace.com> <mailman.19058.1424676730.18130.python-list@python.org> <87bnkkb22u.fsf@jester.gateway.pace.com> <mailman.19111.1424738135.18130.python-list@python.org> <87lhjnang1.fsf@jester.gateway.pace.com>
Date 2015-02-24 16:57 +1100
Subject Re: Are threads bad? - was: Future of Pypy?
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.19118.1424757423.18130.python-list@python.org> (permalink)

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On Tue, Feb 24, 2015 at 4:27 PM, Paul Rubin <no.email@nospam.invalid> wrote:
>> Sure, your code might not be making any mutations (that you know of),
>> but malloc definitely is [1], and that's just the tip of the iceberg.
>> Other things like buffers for stdin and stdout, DNS resolution etc.
>> all have the same issue.
>
> Re stdin/stdout: obviously you can't have
> multiple threads messing with the same fd's; that's the same thing as
> data sharing.

Actually, you can quite happily have multiple threads messing with the
underlying file descriptors, that's not a problem. (Though you will
tend to get interleaved output. But if you always produce output in
single blocks of text that each contain one line with a trailing
newline, you should see interleaved lines that are each individually
correct. I'm also not sure of any sane way to multiplex stdin -
merging output from multiple threads is fine, but dividing input
between multiple threads is messy.) The problem is *buffers* for stdin
and stdout, where you have to be absolutely sure that you're not
trampling all over another thread's data structures. If you unbuffer
your output, it's probably going to be thread-safe.

ChrisA

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Thread

Future of Pypy? Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-02-22 12:45 +0000
  Re: Future of Pypy? jkn <jkn_gg@nicorp.f9.co.uk> - 2015-02-22 04:58 -0800
    Re: Future of Pypy? Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-02-22 15:30 +0000
      [OT] - BASIC is still not a bad choice, was Re: Future of Pypy? Michael Torrie <torriem@gmail.com> - 2015-02-23 17:24 -0700
  Re: Future of Pypy? Laura Creighton <lac@openend.se> - 2015-02-22 14:27 +0100
    Re: Future of Pypy? Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-02-22 15:36 +0000
      Re: Future of Pypy? Laura Creighton <lac@openend.se> - 2015-02-22 18:22 +0100
        Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-22 11:02 -0800
          Re: Future of Pypy? Laura Creighton <lac@openend.se> - 2015-02-22 20:51 +0100
            Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-22 12:14 -0800
              Re: Future of Pypy? Laura Creighton <lac@openend.se> - 2015-02-22 23:13 +0100
                Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-22 18:45 -0800
          Re: Future of Pypy? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-23 12:18 +1100
            Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-22 18:04 -0800
              Re: Future of Pypy? Chris Angelico <rosuav@gmail.com> - 2015-02-23 13:16 +1100
              Re: Future of Pypy? Ryan Stuart <ryan.stuart.85@gmail.com> - 2015-02-23 03:16 +0000
                Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-22 19:45 -0800
                Re: Future of Pypy? Ryan Stuart <ryan.stuart.85@gmail.com> - 2015-02-23 04:00 +0000
                Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-22 22:13 -0800
                Re: Future of Pypy? Ryan Stuart <ryan.stuart.85@gmail.com> - 2015-02-23 07:32 +0000
                Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-23 16:11 -0800
                Re: Future of Pypy? Chris Angelico <rosuav@gmail.com> - 2015-02-24 11:31 +1100
                Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-23 17:50 -0800
                Re: Future of Pypy? Chris Angelico <rosuav@gmail.com> - 2015-02-24 13:03 +1100
                Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-23 20:40 -0800
                Re: Future of Pypy? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-24 17:57 +1100
                Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-27 13:40 -0800
                Re: Future of Pypy? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-02-27 18:47 -0500
                Are threads bad? - was: Future of Pypy? Ryan Stuart <ryan.stuart.85@gmail.com> - 2015-02-24 00:35 +0000
                Re: Are threads bad? - was: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-23 21:27 -0800
                Re: Are threads bad? - was: Future of Pypy? Chris Angelico <rosuav@gmail.com> - 2015-02-24 16:57 +1100
                Re: Are threads bad? - was: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-23 22:23 -0800
                Re: Are threads bad? - was: Future of Pypy? Marko Rauhamaa <marko@pacujo.net> - 2015-02-24 10:08 +0200
                Re: Are threads bad? - was: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-24 15:53 -0800
                Re: Are threads bad? - was: Future of Pypy? Marko Rauhamaa <marko@pacujo.net> - 2015-02-25 07:25 +0200
                Re: Are threads bad? - was: Future of Pypy? Marcos Almeida Azevedo <marcos.al.azevedo@gmail.com> - 2015-02-25 13:34 +0800
                Re: Are threads bad? - was: Future of Pypy? Marko Rauhamaa <marko@pacujo.net> - 2015-02-25 07:46 +0200
                Re: Are threads bad? - was: Future of Pypy? Chris Angelico <rosuav@gmail.com> - 2015-02-25 16:54 +1100
                Re: Are threads bad? - was: Future of Pypy? Marcos Almeida Azevedo <marcos.al.azevedo@gmail.com> - 2015-02-25 13:58 +0800
                Re: Are threads bad? - was: Future of Pypy? Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-24 23:02 -0700
                Re: Are threads bad? - was: Future of Pypy? Chris Angelico <rosuav@gmail.com> - 2015-02-25 17:07 +1100
                Re: Are threads bad? - was: Future of Pypy? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-02-25 16:37 +0000
                Re: Are threads bad? - was: Future of Pypy? Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-25 10:00 -0700
                Re: Are threads bad? - was: Future of Pypy? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-02-25 17:16 +0000
                Re: Are threads bad? - was: Future of Pypy? Chris Angelico <rosuav@gmail.com> - 2015-02-26 04:22 +1100
                Re: Are threads bad? - was: Future of Pypy? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-02-25 19:44 -0500
                Re: Are threads bad? - was: Future of Pypy? Ryan Stuart <ryan.stuart.85@gmail.com> - 2015-02-25 00:59 +0000
                Re: Are threads bad? - was: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-26 21:55 -0800
              Re: Future of Pypy? Chris Angelico <rosuav@gmail.com> - 2015-02-23 14:25 +1100
              Re: Future of Pypy? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-23 18:41 +1100
                Re: Future of Pypy? Marko Rauhamaa <marko@pacujo.net> - 2015-02-23 10:16 +0200
                Re: Future of Pypy? Chris Angelico <rosuav@gmail.com> - 2015-02-23 20:19 +1100
                Re: Future of Pypy? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-24 17:56 +1100
                Re: Future of Pypy? Chris Angelico <rosuav@gmail.com> - 2015-02-24 18:16 +1100
                Re: Future of Pypy? wxjmfauth@gmail.com - 2015-02-23 23:57 -0800
                Re: Future of Pypy? Ethan Furman <ethan@stoneleaf.us> - 2015-02-23 11:39 -0800
                Re: Future of Pypy? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-24 13:15 +1100
                Re: Future of Pypy? Paul Rubin <no.email@nospam.invalid> - 2015-02-23 17:47 -0800
                Re: Future of Pypy? Marko Rauhamaa <marko@pacujo.net> - 2015-02-24 10:12 +0200
      Re: Future of Pypy? Emile van Sebille <emile@fenx.com> - 2015-02-24 09:57 -0800
  Re: Future of Pypy? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-23 01:05 +1100
    Re: Future of Pypy? Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-02-22 15:44 +0000
      Re: Future of Pypy? Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-02-22 19:20 +0000
        Re: Future of Pypy? Laura Creighton <lac@openend.se> - 2015-02-22 22:45 +0100
          Re: Future of Pypy? Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-02-23 14:04 +0000
            Re: Future of Pypy? Laura Creighton <lac@openend.se> - 2015-02-23 17:16 +0100
  Re: Future of Pypy? Terry Reedy <tjreedy@udel.edu> - 2015-02-23 01:34 -0500
  Re: Future of Pypy? Dave Cook <davecook@nowhere.net> - 2015-02-23 11:36 +0000
    Re: Future of Pypy? Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-02-23 14:13 +0000
      Cython - was: Future of Pypy? Stefan Behnel <stefan_ml@behnel.de> - 2015-02-23 16:43 +0100
      Re: Future of Pypy? Dave Cook <davecook@nowhere.net> - 2015-02-23 23:23 +0000

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