[nas] NAS freezing up

[David Woodfall]

On (11/04/13 18:43), David Woodfall <dave at dawoodfall.net> put forth the proposition:
>On (11/04/13 15:05), David Woodfall <dave at dawoodfall.net> put forth the proposition:
>>On (11/04/13 14:46), David Woodfall <dave at dawoodfall.net> put forth the proposition:
>>>On (10/04/13 08:39), Paul Fox <pgf at foxharp.boston.ma.us> put forth the proposition:
>>>>erik wrote:
>>>>>Hi,
>>>>>
>>>>>On Wed, Apr 10, 2013 at 05:26:26AM +0100, David Woodfall wrote:
>>>>>>I've been using nas a while now and I'm finding that it seems to
>>>>>>freeze up at times. It happens randomly and is hard to predict. I have
>>>>>>to kill -9 it, restart it, hit play on umplayer to continue watching.
>>>>>>
>>>>>>Is there any way of debugging this? I've tried running it with verbose
>>>>>>but nothing is showing in the console.
>>>>>
>>>>>By default, all logging is via syslog. There is a debug option available as
>>>>>well that increases the info over verbose.
>>>
>>>I can't see anything useful in the log even with debug at 99.. there's
>>>also nothing useful in mplayer output. I may have a go at an strace
>>>although I fear the strace log is going to huge since it happens maybe
>>>every other movie or so.
>>>
>>>I never saw this behaviour until I upgraded my old media box from an
>>>old Athlon XP 32bit to a new dual core 64bit machine. I'm wondering if
>>>it's a hardware or even network problem. Not quite sure where to look
>>>at the moment.
>>
>>I think I can say that it isn't a network problem - I just pulled the
>>network cable on my laptop while playing and I only had to pause/play
>>mplayer and it continued with no problem and without having to restart
>>nasd.
>>
>>I also checked the dates of my /dev/dsp* to see whether perhaps
>>something flakey was happening with the USB output but they haven't
>>been recreated since I booted the box up some months back.
>>
>>>>i've been seeing this as well, though i think it started for me when i
>>>>began running nasd via /usr/bin/aoss, to get it to play well with alsa
>>>>(in particular, dmix).
>>
>>What is your output device? USB, SPDIF, analog? My old box used coax
>>and optical, but this new one only has onboard USB and analog outs 
>>since I haven't yet bought a decent sound card for it. Wondering if 
>>the
>>onboard USB is flakey...
>>
>>>>when i've strace'd a hung process, it's always been stuck on a futex
>>>>call, but that doesn't narrow it down much.
>
>Strace log is here: http://www.dawoodfall.net/nasd/strace.log

Looking at the end of that, before my term and kill signals, it also
looks like a futex call:

17717 18:34:34 futex(0x7f5068800720, FUTEX_WAIT_PRIVATE, 2, NULL) = ?
ERESTARTSYS (To be restarted)

I'm not a C programmer, but it looks like it should restart the
system call, and it isn't - it appears to be stuck on a
FUTEX_WAIT_PRIVATE