On Sat, Jul 11, 2015 at 02:23:03PM +0200, Mark Kettenis wrote: > Every now and then sndiod hangs on me. Usually I discover this as > mplayer hangs while playing a video or hangs while opening the audio > device on startup. Restarting sndiod using the /etc/rc.d/sndiod > script doesn't work; it blocks trying to stop the running sndiod. I > have to use kill -9 to get rid of it. > > Happened again last night and I investigated a bit. This was after I > tried restarting it using /etc/rc.d/sndiod, but before resorting to > kill -9. Attaching with gdb revealed that it was stuck in poll(2) > with the 2nd argument being 0 and the last argument being -1. Since > no file descriptors are being monitored and the timeout is infinite, > the process just blocks forevere.
noemally it gets periodic SIGALRM which interrupt poll(2) with EINTR. > I did look at the file_list, and only the rsnd/0 file descriptor was > on the list. That probably corresponded to the mplayer that hung (and > which I subsequently killed) as I had nothing else running that was > doing audio output. Obviously the sndiod polling code had decided not > to poll for activity on rsnd/0, causing it to block as described > above. if there are no clients, rsnd/0 is supposed to be closed, very strange
