Subj : Re: reliability of setting thread priority
To   : comp.programming.threads
From : gottlobfrege
Date : Fri Feb 25 2005 04:41 am


Alexander Terekhov wrote:
> gottlobfrege@gmail.com wrote:
> [...]
> >   In particular, similar to the problems of static local
initializers
> > and implementing pthread_once, etc., I want to initialize a
critical
> > section in a thread safe manner.
>
> http://groups.google.de/groups?selm=3FA61F96.223FDE85%40web.de
>
> >                                   I would use another critical
section
> > to guard the first CS, but that 'begs the question' as they say.
:-)  I
> > could use a global named mutex (CreateMutex() under Win32), but
that
> > seems a bit heavy - and if I was going to use a mutex to make a
> > criticalsection, maybe I should just use a mutex where the CS was
going
> > in the first place.
>
> Named mutex doesn't live long. It is used to serialize event
> creation/init (and initial lock state change). Once it is done,
> CloseHandle() is called. So what's your problem (priorities
> aside for a moment)?
>
> regards,
> alexander.

No real problem, but a Win32 Mutex is about 5x slower than a
criticalsection, and about 15x slower than using atomic exchanges.
(Rough numbers)

I had a real life case where there was possibly going to be 100s of
these objects used, so speed matters.

On the other hand, a would consider using a mutex for the portable
version, if anyone thought that the priority setting stuff was
problematic - correctness beats speed (almost) every time...

Tony

.