John Wendel wrote:
Douglas Phillipson wrote:
This probably isn't a Fedora specific question so I apologize if this
is the wrong forum.
Anybody know if you can set more than one interval timer in a single
process?
(setitimer())
Would starting more than one interval timer in a single process
confuse the signal system when delivering the SIGALRM to the receiving
process?
In other words, can I have a 10 second interval timer which when times
out delivers a sigalrm to one function, and in the same process have a
1 second interval timer set to give a sigalrm to another function?
I'm having trouble with a second interval timer, it doesn't seem to
work, or deliver the signal to the desired function. I'm using a
separate instance of struct itimerval and struct sigaction when
setting up the timers. I have several books on the subject of
interval timers but none say you shouldn't do this, just "Every
process has its own set of timers". But they might be referring to
REAL, VIRTUAL, and PROF timers, a single set of these for each process.
Opinions requested...
Thanks
Doug P
I'm not an expert on this stuff, but my understanding is that setitimer
gives your process access to one of three predefined timers (REAL,
VIRTUAL, and PROF) and only the REAL timer is actually useful.
So your second call to setitimer is mucking up the settings from the
first call.
See "man timer_create" for the POSIX timer stuff that lets you have lots
of timers.
I recommend the O'REILLY book POSIX 4 by Bill Gallmeister for a good
explanation of this fairly complicated topic.
Regards,
John
My result on the timer issue is that a interval timer won't call its
timeout function while msgrcv() is waiting for a message on a queue.
Regards
Doug P
