[mythtv-users] backend crashes

junk junk at giantblob.com
Wed Jan 31 22:03:27 UTC 2007


My backend seems to be going through periods where it repeatedly dies 
and I'm not sure how to determine the cause of it. Sometimes it'll run 
fine for a day or two and I can make a number of scheduled recordings 
and/or watch live-tv, other times it'll die on me without warning, 
sometimes several times an hour. I don't get much indication in the log 
beyond seeing 'Starting up as the master server.' as it restarts after 
(presumably) crashing.

Firstly, is there any way to force it print a backtrace when it dies? 
It's running as a service started by init - does anyone know how to edit 
the Gentoo /etc/init.d/mythbackend script to start it under gdb safely 
and generate a backtrace on a fatal signal without requiring any user 
input (so when it suddently dies at 3AM, I don't need to be there to 
watch it!)

Secondly, can anyone hazard a guess at possible causes?

Things that might be relevant:
  - I'm running a single tuner dvb setup on a vanilla kernel
  - my dvb reception is poor but backend crashes don't seem particularly 
correlated with periods of particularly poor reception/bursts of errors 
in the received MPEG2 stream - sometimes I can record hours of 
programming with masses of reported errors in the stream and visible 
glitches, other times the back end will die repeatedly with no reported 
errors in received stream.
  - I've tried messing with PCI latencies, but put them back to defaults 
when it didn't seem to help
  - I have mythcommflag running sometimes, I suspect it might be 
contributing to the problem - is this possible?
  - All my filesystems are XFS, so autoexpire delete storm is not a 
likely cause?
  - Machine has loads of memory (2GB) and 1.8GHz A64 CPU (in 32bit mode) 
- I doubt it's overloaded recording one dvb stream
  - Single ATA disk has bus to itself and DMA is definitely enabled
  - CPU, northbridge, memory and disk are all cool and I don't believe 
the hardware is flakey (it's previously been running quite heavy Linux 
loads without any odd behavior before being repurposed as my MythTV box)

Any suggestions gratefully received, thanks
-- jeek

More information about the mythtv-users mailing list