Re: Oozing poison

From	Ian Collins <ian-news@hotmail.com>
Newsgroups	comp.lang.c++
Subject	Re: Oozing poison
Date	2012-01-29 11:32 +1300
Message-ID	<9ojbcpF8j0U13@mid.individual.net> (permalink)
References	(7 earlier) <3EEUq.107196$487.32649@news.usenetserver.com> <9ogpsvF8j0U6@mid.individual.net> <qGKUq.152389$624.85025@news.usenetserver.com> <87d3a44es0.fsf@catnip.gol.com> <ROZUq.97141$ka3.2190@news.usenetserver.com>

Show all headers | View raw

On 01/29/12 10:31 AM, Scott Lurndal wrote:
> Miles Bader<miles@gnu.org>  writes:
>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>> The catch is also the reason for all the extra code, constructing and
>>>> destructing a temporary std::exception object.  The actual exception
>>>> handling part of the code is this bit:
>>>
>>> Yet creating and destroying a temporary std::exception object also counts in
>>> terms of both extra cycles and code footprint.   Both of which impact
>>> performance (generally negatively).
>>
>> Er, exceptions are intended to be _exceptional_.
>>
>> If some exception occurs so often that it has a measurable performance
>> impact, it probably shouldn't be an exception.
>
> The exception never occurs (i.e., I never run out of memory).   It's the
> added code to handle the exception and it's effect on a (very) hot codepath
> that causes the 4% hit in performance.   That is the only change in the
> codebase, and I ran the benchmark three times with each flavor (try/catch/new
> vs. malloc).  I have to admit that I was surprised by the difference and I'm
> going to take a look at the actual codepaths and do some profiling to see why
> adding a try/catch clause has such a large effect, when the exception is never
> taken.

How about new (without the exceptions) compared to malloc?  new is doing 
more work than malloc, one reason I suggested a specialised allocator.

-- 
Ian Collins

Thread

Oozing poison AD <isquat@gmail.com> - 2012-01-10 04:35 -0800
  Re: Oozing poison Leigh Johnston <leigh@i42.co.uk> - 2012-01-10 15:19 +0000
    Re: Oozing poison AD <isquat@gmail.com> - 2012-01-11 00:43 -0800
      Re: Oozing poison "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2012-01-11 10:01 +0100
        Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-11 22:09 +1300
          Re: Oozing poison AD <isquat@gmail.com> - 2012-01-11 01:42 -0800
            Re: Oozing poison Leigh Johnston <leigh@i42.co.uk> - 2012-01-11 13:36 +0000
              Re: Oozing poison John Bokma <john@castleamber.com> - 2012-01-11 10:08 -0600
              Re: Oozing poison AD <isquat@gmail.com> - 2012-01-12 06:08 -0800
                Re: Oozing poison Leigh Johnston <leigh@i42.co.uk> - 2012-01-12 14:13 +0000
                Re: Oozing poison AD <isquat@gmail.com> - 2012-01-17 02:08 -0800
                Re: Oozing poison Henrik Faber <hfaber@invalid.net> - 2012-01-17 12:50 +0100
                Re: Oozing poison Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-13 02:18 -0800
                Re: Oozing poison AD <isquat@gmail.com> - 2012-01-17 02:24 -0800
      Re: Oozing poison Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-11 16:50 +0000
        Re: Oozing poison AD <isquat@gmail.com> - 2012-01-12 06:04 -0800
          Re: Oozing poison Victor Bazarov <v.bazarov@comcast.invalid> - 2012-01-12 10:13 -0500
            Re: Oozing poison AD <isquat@gmail.com> - 2012-01-17 02:19 -0800
              Re: Oozing poison Victor Bazarov <v.bazarov@comcast.invalid> - 2012-01-17 08:04 -0500
              Re: Oozing poison Miles Bader <miles@gnu.org> - 2012-01-18 13:51 +0900
                Re: Oozing poison AD <isquat@gmail.com> - 2012-01-21 04:40 -0800
                Re: Oozing poison Quint Rankid <qbr567@gmail.com> - 2012-01-21 09:05 -0800
                Re: Oozing poison Wil Evers <bouncer@dev.null> - 2012-01-21 18:52 +0000
                Re: Oozing poison Quint Rankid <qbr567@gmail.com> - 2012-01-21 11:33 -0800
                Re: Oozing poison AD <isquat@gmail.com> - 2012-01-25 02:23 -0800
                Re: Oozing poison AD <isquat@gmail.com> - 2012-01-25 02:07 -0800
                Re: Oozing poison Victor Bazarov <v.bazarov@comcast.invalid> - 2012-01-25 07:59 -0500
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-26 07:54 +1300
                Re: Oozing poison Pavel <pauldontspamtolk@removeyourself.dontspam.yahoo> - 2012-01-21 22:43 -0500
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-22 21:05 +1300
                Re: Oozing poison Pavel <pauldontspamtolk@removeyourself.dontspam.yahoo> - 2012-01-22 18:21 -0500
                Re: Oozing poison Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-23 15:55 +0000
                Re: Oozing poison gwowen <gwowen@gmail.com> - 2012-01-23 08:37 -0800
                Re: Oozing poison Pavel <pauldontspamtolk@removeyourself.dontspam.yahoo> - 2012-01-24 22:48 -0500
                Re: Oozing poison Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-25 19:44 +0000
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-26 08:56 +1300
                Re: Oozing poison 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-25 23:04 -0800
                Re: Oozing poison Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-26 03:24 -0800
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-26 19:13 +0000
                Re: Oozing poison Brian Drummond <brian@shapes.demon.co.uk> - 2012-01-27 00:12 +0000
                Re: Oozing poison "MikeWhy" <boat042-nospam@yahoo.com> - 2012-01-26 22:44 -0600
                Re: Oozing poison 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-28 14:25 -0800
                Re: Oozing poison Robert Miles <milesrf@Usenet-News.net> - 2012-02-26 22:16 -0600
              Re: Oozing poison "Gernot Frisch" <me@privacy.net> - 2012-01-24 18:21 +0100
                Re: Oozing poison Victor Bazarov <v.bazarov@comcast.invalid> - 2012-01-24 12:41 -0500
                Re: Oozing poison Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-26 03:25 -0800
              Re: Oozing poison Rui Maciel <rui.maciel@gmail.com> - 2012-01-25 19:44 +0000
                Re: Oozing poison Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-26 09:44 +0000
                Re: Oozing poison Rui Maciel <rui.maciel@gmail.com> - 2012-01-26 10:36 +0000
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-26 19:18 +0000
                Re: Oozing poison Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-26 20:42 +0000
                Re: Oozing poison Juha Nieminen <nospam@thanks.invalid> - 2012-01-26 16:30 +0000
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-26 19:24 +0000
                Re: Oozing poison Cholo Lennon <chololennon@hotmail.com> - 2012-01-26 17:13 -0300
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-26 20:55 +0000
                Re: Oozing poison Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-26 22:08 +0000
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-27 00:32 +0000
                Re: Oozing poison Dombo <dombo@disposable.invalid> - 2012-01-28 12:59 +0100
                Re: Oozing poison Cholo Lennon <chololennon@hotmail.com> - 2012-01-27 18:28 -0300
                Re: Oozing poison Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-29 18:02 +0000
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-27 20:18 +1300
                Re: Oozing poison Miles Bader <miles@gnu.org> - 2012-01-27 18:09 +0900
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-27 20:29 +0000
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-28 10:06 +1300
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-27 21:26 +0000
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-28 12:22 +1300
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-28 04:18 +0000
                Re: Oozing poison Miles Bader <miles@gnu.org> - 2012-01-28 13:44 +0900
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-28 21:31 +0000
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-29 11:32 +1300
                Re: Oozing poison 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-28 14:55 -0800
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-29 11:59 +1300
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-30 17:08 +0000
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-28 18:06 +1300
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-28 22:49 +0000
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-29 12:22 +1300
                Re: Oozing poison scott@slp53.sl.home (Scott Lurndal) - 2012-01-27 20:16 +0000
                Re: Oozing poison Ian Collins <ian-news@hotmail.com> - 2012-01-28 10:01 +1300
                Re: Oozing poison Juha Nieminen <nospam@thanks.invalid> - 2012-01-28 16:00 +0000
  Re: Oozing poison Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-10 21:42 +0000
    Re: Oozing poison AD <isquat@gmail.com> - 2012-01-17 02:31 -0800

csiph-web