Subj : Re: double-checked locking in C
To   : comp.programming.threads
From : David Schwartz
Date : Fri Jul 08 2005 07:09 am


"Joe Seigh" <jseigh_01@xemaps.com> wrote in message 
news:DPWdnS07t_9x7lPfRVn-vA@comcast.com...

> Posix guarantees aren't formally defined.  The test suites no more prove
> the implementation is "correct" any more than testing a multi-threaded 
> program
> proves it is "correct".

    You are seriously arguing that the test suites give you no idea whether 
programs similar to the test suites will work?

> And yes, your code is future proof if you don't actually use anything new 
> and
> your compiler and runtime still exist.   And your posix pthreads programs 
> will
> still work as long as you don't try to use anything not anticipated by 
> pthreads
> at the time you wrote the program, and posix pthreads has been ported.

    Your compiler and runtime don't have to exist. You just have to have not 
done anything bizarre that isn't anticipated by the standards and the people 
who supply the implementations of them. I'm advocating not doing anything 
bizarre and you are saying it doesn't matter.

> But DCL is just as portable as pthreads in that somebody has to know what 
> both
> are supposed to do in order to do the port.

    But we aren't talking about porting DCL versus porting pthreads. The 
choice is not "should I use DCL or should I use pthreads". The choice is 
"should I comply with the standards such that later implementations of the 
standard will still work with my code so long as they comply with the 
standards or should I use code that happens to work and doesn't conform to 
the standards and have to deal with any future problems myself".

> Really, this is getting almost as tiresome as the "C has nothing to do 
> with threads"
> refrain in the C/C++ newsgroups when confronted by anything outside of 
> their closed
> universe.  If you want to ignore stuff that's strictly not Posix pthreads, 
> fine.
> Ignore it.   But this is not comp.programming.pthreads and posix heresy is 
> not a mortal
> sin here.

    This has nothing special to do with POSIX pthreads. The argument would 
be precisely the same if we were talking about WIN32 threads. On WIN32, 
there are things that are guaranteed and things that happen to work. If you 
use the things that are guaranteed, you can be reasonably assured that your 
code will continue to work on future WIN32 platforms. If you use things that 
happen to work, you had better be prepared to maintain you code or see it 
break on future hardware.

    DS

.