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

References	(18 earlier) <87zj82bm15.fsf@elektro.pacujo.net> <mailman.19167.1424842476.18130.python-list@python.org> <87pp8ybl14.fsf@elektro.pacujo.net> <CAPTjJmoa6Rc8EZ4SxsamNPeCYzcY47AzNzVWxBvXydfp=gn-aA@mail.gmail.com> <CALwzid=mRRZ9Ko9RDnUTN0_z9y82-ENR=pJRtsxXP+=Sk_zXPA@mail.gmail.com>
Date	2015-02-25 17:07 +1100
Subject	Re: Are threads bad? - was: Future of Pypy?
From	Chris Angelico <rosuav@gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.19171.1424844457.18130.python-list@python.org> (permalink)

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On Wed, Feb 25, 2015 at 5:02 PM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
>> Uhh, I have seen *heaps* of code whose performance suffers from too
>> much locking. At the coarsest and least intelligent level, a database
>> program that couldn't handle concurrency at all, so I wrote an
>> application-level semaphore that stopped two people from running it at
>> once. You want to use that program? Ask the other guy to close it.
>> THAT is a performance problem. And there are plenty of narrower cases,
>> where it ends up being a transactions-per-second throughput limiter.
>
> Is the name of that database program "Microsoft Access" perchance?

No, though it wouldn't surprise me if it had the same issue. No, the
program was a DBase-backed one of my own development; it was the DBase
engine itself that couldn't handle concurrency, so I added some
startup code that checked to see if anyone else had the file open, and
popped up a "retry or cancel" prompt until the semaphore cleared.

Later on, I was able to shift the entire content into DB2 (once we no
longer needed compatibility with an even older DBase-backed program),
and voila, we had concurrency. I still needed to make use of
record-level locking (if you open a record for editing, it holds a
lock for as long as you have the window open; chances are, anyone else
who wants the same record is actually doing the same job, so erroring
out is the best option), but no more database-level locks.

ChrisA

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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