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Re: The threading specs in the standard: a new catastrophe

Cross-posted to 2 groups.

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Jens Gustedt wrote:
> Am 10.07.2011 00:02, schrieb Marcin Grzegorczyk:
>> No such thing is implied in the draft Standard.  The reason is that some
>> existing mutex implementations do not provide static initialization;
>> most notably, under Win32, neither mutex objects nor critical section
>> objects do (barring some tricks that may break if Microsoft decides to
>> change the underlying implementation, again).
>
> Hm, I first thought that a once_flag could be used to launch an
> initializer function for such statically objects. As such this is not
> possible, since the call_once interface doesn't allow the function
> parameter to receive an argument.
>
> But an implementation would have to provide call_once & Co. So you'd
> have to have
> - some sort of atomic read of the once_flag
> - the potential to delay all but one threads that stumble into this
>    simultaneaously

Yes; indeed, that's how one implements Win32 critical section 
initialization when explicit initialization is not feasible for some 
reason (and one doesn't want to rely on undocumented tricks).

> These ingredients could be used equally well to call an mtx_init and
> cnd_init on statically initialized objects, I think. Performance cost
> of such things should be minor.

One problem is, what to do if the actual initialization of the mutex 
(which may entail allocation of system resources) fails.  POSIX simply 
states that things should be implemented such that it cannot fail (see 
the Rationale section of 
<http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_mutex_init.html>), 
but it's not realistic to put such a requirement on all implementations; 
and allowing mtx_*lock() to return thrd_nomem would be a divergence from 
the pthreads practice.

Of course, what I just said does not mean WG14 cannot yet reconsider 
this point; I just consider it unlikely.
-- 
Marcin Grzegorczyk

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The threading specs in the standard: a new catastrophe jacob navia <jacob@spamsink.net> - 2011-07-07 12:33 +0200
  Re: The threading specs in the standard: a new catastrophe Juha Niskanen <juniskan@paju.oulu.fi.nospam> - 2011-07-07 12:46 +0000
    Re: The threading specs in the standard: a new catastrophe jacob navia <jacob@spamsink.net> - 2011-07-07 17:26 +0200
  Re: The threading specs in the standard: a new catastrophe Todd Carnes <toddcarnes@gmail.com> - 2011-07-07 13:12 +0000
    Re: The threading specs in the standard: a new catastrophe jacob navia <jacob@spamsink.net> - 2011-07-07 17:11 +0200
      Re: The threading specs in the standard: a new catastrophe lawrence.jones@siemens.com - 2011-07-08 09:23 -0400
      Re: The threading specs in the standard: a new catastrophe Todd Carnes <toddcarnes@gmail.com> - 2011-07-08 15:20 +0000
  Re: The threading specs in the standard: a new catastrophe "christian.bau" <christian.bau@cbau.wanadoo.co.uk> - 2011-07-07 07:36 -0700
    Re: The threading specs in the standard: a new catastrophe jacob navia <jacob@spamsink.net> - 2011-07-07 17:09 +0200
      Re: The threading specs in the standard: a new catastrophe Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-07 18:00 +0200
        Re: The threading specs in the standard: a new catastrophe jacob navia <jacob@spamsink.net> - 2011-07-07 18:20 +0200
  Re: The threading specs in the standard: a new catastrophe Wojtek Lerch <wojtek_l@yahoo.ca> - 2011-07-07 12:31 -0400
    Re: The threading specs in the standard: a new catastrophe Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-07-07 09:40 -0700
      Re: The threading specs in the standard: a new catastrophe Wojtek Lerch <wojtek_l@yahoo.ca> - 2011-07-07 14:42 -0400
        Re: The threading specs in the standard: a new catastrophe Chad <cdalten@gmail.com> - 2011-07-07 12:03 -0700
          Re: The threading specs in the standard: a new catastrophe Angel <angel+news@spamcop.net> - 2011-07-07 19:27 +0000
    Re: The threading specs in the standard: a new catastrophe Ian Collins <ian-news@hotmail.com> - 2011-07-08 09:14 +1200
      Re: The threading specs in the standard: a new catastrophe Wojtek Lerch <wojtek_l@yahoo.ca> - 2011-07-07 23:58 -0400
        Re: The threading specs in the standard: a new catastrophe Ian Collins <ian-news@hotmail.com> - 2011-07-08 16:24 +1200
      Re: The threading specs in the standard: a new catastrophe Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-08 12:14 +0200
        Re: The threading specs in the standard: a new catastrophe Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-10 00:02 +0200
          Re: The threading specs in the standard: a new catastrophe Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-10 14:47 +0200
            Re: The threading specs in the standard: a new catastrophe Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-11 21:05 +0200
              Re: The threading specs in the standard: a new catastrophe Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-11 22:50 +0200
                Re: The threading specs in the standard: a new catastrophe Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-11 23:56 +0200
                Re: The threading specs in the standard: a new catastrophe Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-12 07:50 +0200
                Re: The threading specs in the standard: a new catastrophe Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-16 01:14 +0200
                Re: The threading specs in the standard: a new catastrophe Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-16 10:08 +0200
                Re: The threading specs in the standard: a new catastrophe Miles Bader <miles@gnu.org> - 2011-07-18 11:11 +0900
                Re: The threading specs in the standard: a new catastrophe Alexander Terekhov <terekhov@web.de> - 2011-07-18 21:50 +0200
                Re: The threading specs in the standard: a new catastrophe Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-19 08:36 +0200
                Re: The threading specs in the standard: a new catastrophe Alexander Terekhov <terekhov@web.de> - 2011-07-21 11:56 +0200
                Re: The threading specs in the standard: a new catastrophe Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-22 20:31 +0200
                Re: The threading specs in the standard: a new catastrophe Alexander Terekhov <terekhov@web.de> - 2011-07-22 21:36 +0200
                Re: The threading specs in the standard: a new catastrophe Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-23 10:50 +0200
                Re: The threading specs in the standard: a new catastrophe Alexander Terekhov <terekhov@web.de> - 2011-07-23 20:29 +0200
                Re: The threading specs in the standard... Alexander Terekhov <terekhov@web.de> - 2011-08-03 15:50 +0200
  Re: The threading specs in the standard: a new catastrophe Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-07 23:07 +0200
    Re: The threading specs in the standard: a new catastrophe jacob navia <jacob@spamsink.net> - 2011-07-07 23:32 +0200
      Re: The threading specs in the standard: a new catastrophe jameskuyper <jameskuyper@gmail.com> - 2011-07-07 15:25 -0700
        Re: The threading specs in the standard: a new catastrophe sfuerst <svfuerst@gmail.com> - 2011-07-07 16:12 -0700
          Re: The threading specs in the standard: a new catastrophe James Kuyper <jameskuyper@verizon.net> - 2011-07-07 22:41 -0400
          Re: The threading specs in the standard: a new catastrophe "Chris M. Thomasson" <cristom@charter.net> - 2011-07-08 12:47 -0700
            Re: The threading specs in the standard: a new catastrophe sfuerst <svfuerst@gmail.com> - 2011-07-08 13:11 -0700
              Re: The threading specs in the standard: a new catastrophe "Chris M. Thomasson" <cristom@charter.net> - 2011-07-08 16:56 -0700
              Re: The threading specs in the standard: a new catastrophe Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-09 23:55 +0200
                Re: The threading specs in the standard: a new catastrophe sfuerst <svfuerst@gmail.com> - 2011-07-09 18:40 -0700
        Re: The threading specs in the standard: a new catastrophe jacob navia <jacob@spamsink.net> - 2011-07-08 01:16 +0200
          some sane words, for sure "Greg A. Woods" <woods@robohack.org> - 2011-07-07 18:33 -0700
          Re: The threading specs in the standard: a new catastrophe jameskuyper <jameskuyper@gmail.com> - 2011-07-08 08:34 -0700
            Re: The threading specs in the standard: a new catastrophe sfuerst <svfuerst@gmail.com> - 2011-07-08 10:47 -0700
              Re: The threading specs in the standard: a new catastrophe James Kuyper <jameskuyper@verizon.net> - 2011-07-09 06:57 -0400
                Re: The threading specs in the standard: a new catastrophe Alexander Terekhov <terekhov@web.de> - 2011-07-09 13:59 +0200
                Re: The threading specs in the standard: a new catastrophe jacob navia <jacob@spamsink.net> - 2011-07-09 14:45 +0200
                Re: The threading specs in the standard: a new catastrophe "Chris M. Thomasson" <cristom@charter.net> - 2011-07-10 15:47 -0700
                Re: The threading specs in the standard: a new catastrophe Alexander Terekhov <terekhov@web.de> - 2011-07-11 13:38 +0200
                Re: The threading specs in the standard: a new catastrophe Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-07-11 16:12 +0300
      Re: The threading specs in the standard: a new catastrophe "MikeP" <mp011011@some.org> - 2011-07-07 23:32 -0500
      Re: The threading specs in the standard: a new catastrophe lawrence.jones@siemens.com - 2011-07-08 10:09 -0400
        Re: The threading specs in the standard: a new catastrophe Shao Miller <sha0.miller@gmail.com> - 2011-07-08 10:31 -0400
  Re: The threading specs in the standard: a new catastrophe Tim Rentsch <txr@alumni.caltech.edu> - 2011-07-07 14:32 -0700
  Re: The threading specs in the standard: a new catastrophe Shao Miller <sha0.miller@gmail.com> - 2011-07-08 00:38 -0400
  Re: The threading specs in the standard: a new catastrophe Ian Collins <ian-news@hotmail.com> - 2011-07-08 17:10 +1200
    Re: The threading specs in the standard: a new catastrophe James Kuyper <jameskuyper@verizon.net> - 2011-07-08 07:46 -0400
      Re: The threading specs in the standard: a new catastrophe Ian Collins <ian-news@hotmail.com> - 2011-07-08 23:52 +1200
        Re: The threading specs in the standard: a new catastrophe James Kuyper <jameskuyper@verizon.net> - 2011-07-08 08:23 -0400
          Re: The threading specs in the standard: a new catastrophe jacob navia <jacob@spamsink.net> - 2011-07-08 14:54 +0200
          Re: The threading specs in the standard: a new catastrophe Ian Collins <ian-news@hotmail.com> - 2011-07-09 08:26 +1200
        Re: The threading specs in the standard: a new catastrophe Seebs <usenet-nospam@seebs.net> - 2011-07-08 14:47 +0000
  Re: The threading specs in the standard: a new catastrophe Juha Niskanen <juniskan@paju.oulu.fi.nospam> - 2011-07-08 07:52 +0000
    Re: The threading specs in the standard: a new catastrophe jacob navia <jacob@spamsink.net> - 2011-07-09 14:23 +0200
    Re: The threading specs in the standard: a new catastrophe Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-10 00:59 +0200
      Re: The threading specs in the standard: a new catastrophe Keith Thompson <kst-u@mib.org> - 2011-07-09 19:05 -0700

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