(OT) Semaphore/signalling question

[Christian Jaeger <ch...@sl.ethz.ch>]

What's the best way to unlock several sister processes waiting for an 
event at once? I just want to tell "now it's ready, go on". An idea 
would be to use normal unix signals, but there are only 32 of them 
(aren't there?) and their management would be rather complicated. I'm 
looking for something like semaphores instead. The problem with 
semaphores is that I don't see a way to release *several* waiting 
processes at once. $n= $sem->getncnt(XX); $sem->op(XX, $n) to 
increment the count for all waiting processes does not work when one 
process is faster (in a loop) than the others and gets away 
everything before the others are unlocked.

Are (unix domain) sockets the right thing for this?

Thanks
Christian.