FreeBSD pthread_equal "bug"

[Julian Elischer]

On Wed, 4 Jun 2003, Julian Elischer wrote:

> in fact The first paragraph of:

uh, not the first parageaph.. the paragraph marked "Thread IDs"
(didn't notice the page was scrolled up a bit)

> 
>  http://www.opengroup.org/onlinepubs/007904975/toc.htm
> 
> States this..
> 
> 
> On Wed, 4 Jun 2003, Julian Elischer wrote:
> 
> > 
> > 
> > On Wed, 4 Jun 2003, Jeff Roberson wrote:
> > 
> > > On 4 Jun 2003, Kern Sibbald wrote:
> > > 
> > > >
> > > > I'm not sure what the POSIX specification says,
> > > > if I were programming it, I would not be content
> > > > with the FreeBSD current implementation especially
> > > > considering that both Solaris and Linux do it "correctly".
> > > 
> > > Would you rather your application failed immediately, or in a subtle,
> > > unexpected way after many hours/weeks/months of run time?  Dan says the
> > > standard allows for immediate reuse.  If that is correct, then Solaris,
> > > linux, and FreeBSD all do it correctly for the only definition of
> > > correctly that matters.
> > > 
> > > Simply adding an ID is problematic because the ids will wrap.  Without
> > > using some deterministic notification you can't be sure that it isn't an
> > > expired thread.
> > 
> > 
> > I will quote from "Programming with Posix threads"
> > by David R Butenhof..
> > He is one o fthe main authors of the Posix threads standard so 
> > I tend to treat this book as a guide..
> > 
> > "Once a thread is recycled, the thread's ID (pthread_t) is no longer
> > valid. You cannot join with the thread, canel it, or anything else. The
> > terminated thread's ID (which may be the addess of a system data
> > structure) may be assigned to a new thread. Instead of receiving an
> > ESRCH failure from your call to pthread_cancel, you would instead cancel
> > a different thread."
> > 
> > I think that is pretty explicit as far as expected bahaviour.
> > 
> > HAVING SAID THAT, it is not impossible that at some time in the future
> > we may use some other pthread_t type, e.g an incrementing TID,
> > but at this time I think we are well within the standard...
> > 
> > 
> > Julian
> > 
> > 
> > _______________________________________________
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> > 
> 
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