Subj : Re: Futexes are wrong! (Are they?)
To   : comp.programming.threads
From : Marcin 'Qrczak' Kowalczyk
Date : Mon Jun 06 2005 12:56 pm

"Jomu" <dragisha@gmail.com> writes:

> As consumer-producer message queues are (for me, probably elsewhere
> also) most frequent sync devices, and their problem with preemptive
> signaling happens mostly (maybe only) when one thread signals while
> holding mutex (same one waiting thread will try to reacquire when
> signaled) then why don't rearrange signaling so that it happens
> after mutex is freed?

I guess it will work in this case.

Unfortunately in the case I have pthread_cond_{broadcast,signal}
is followed by pthread_cond_wait, so I can't move signalling after
unlocking and additional context switches are pointless.

BTW, is it better to use pthread_cond_broadcast or pthread_cond_signal
when I know that only one thread is waiting?

-- 
   __("<         Marcin Kowalczyk
   \__/       qrczak@knm.org.pl
    ^^     http://qrnik.knm.org.pl/~qrczak/

.