Subj : Re: timer thread & signal question
To   : comp.programming.threads
From : Loic Domaigne
Date : Fri Jan 07 2005 06:41 am

Hello VK,

> Please help me with this newbie problem.  I'm trying to set up a timer
> thread with the signal handler.  My problem is that when I have 2
> timers that go off at the same time, the signal SIGUSR2 is sent twice
> to sigwait(), but since they are 2 identical signals, sigwait() sees it
> as 1 signal only.  How do I tell sigwait() that there are 2 of the same
> signal?

SIGUSR2 is not queued. If you sent it x times, the process shall only 
receive it one time (this has less to do with sigwait() actually).

You must used queued signal. If your implementation supports it, use 
realtime signal: signal whose number is between SIGRTMIN and SIGRTMAX.


> I tried sigwaitinfo() also as I thought sigwaitinfo() "returns the
> queued signal value so that applications can differentiate between
> multiple events queued to the same signal number".  But it didn't do it
> :(

Try your luck with realtime signal. Try for instance with RTMIN+2 (some 
pthread implementation uses internally RTMIN and RTMIN+1).


HTH,
Loic.

.