Re: [Threads-devel] More problems with condition

From: Patrick Twohig (p-twohig_at_[hidden])
Date: 2008-04-20 15:56:27

I've read doug Schmidt's paper a little while back when I was trying to
implemented a condition variable on a system lacking support for it.
Additionally, SignalObjectAndWait was not available because the code used
CriticalSections instead of Windows Mutexes so I ended up  basing the
implementation on some code I found which used a deque of signals to notify
one or all threads.  I don't know if that approach introduces fairness
problems or not, but it seemed to work for me.  I'm certainly not suggesting
tearing apart all the code in boost::condition_variable with something
similar, but I was just more comparing boost's implementation with with a
different implementation I had found.

On Sun, Apr 20, 2008 at 9:09 AM, Kimon Hoffmann <
Kimon.Hoffmann_at_[hidden]> wrote:

> Hi Anthony,
>
> Anthony Williams wrote:
>
> > Quoting Anteru <newsgroups_at_[hidden]>:
> >
> >>
>
> > Well, I still have problems with the conditions, even with the latest
> > > SVN.
> > >
> >
> > Yes, the win32 spurious-wake-prevention code is faulty. The one-line
> >  fix I originally suggested is better in that it does actually work, at  the
> > expense of more spurious wakes.
> >
> > I'm working on a new spurious-wake-prevention mechanism. I'm really
> >  frustrated that this hasn't come to light until now.
> >
>
> Just FYI, last Thursday we encountered a similar/the same problem with the
> new threading code and filed a Trac ticket. The ticket number is #1834.
> For now we have resorted to switching back to Boost 1.34.1 but since Boost
> 1.35.0 includes a few important fixes to other libraries it would be really
> great if a fix for this would make it into 1.35.1.
>
> One question about the spurious-wake-prevention: Is the absence of
> spurious wakes one of the guarantees made by the threading library proposal?
>
> Best regards,
>  Kimon
>
>
>
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