[mythtv-users] Could realtime commercial flagging cause hard lockup/freeze/hang?

Roger Heflin rogerheflin at gmail.com
Wed Jun 4 02:44:45 UTC 2008

Greg Grotsky wrote:
> Hello all,
>   I've been a mythtv user for a few years.  My configuration is a single
> system frontend/backend.  Since it's inception I have been using realtime
> commercial flagging and it has worked very well.  However, I recently
> updated my mythtv svn tree (to 17392 from an update 5/3/08) and every once
> in a while the system completely hangs.  It hangs to the point where the
> magic Alt-SysRq-REISUB does not reboot it, no SSH, no three-fingered-salute,
> no nothing.
>   I get nothing in my logs (FE, BE, syslog, messages, etc) and it appears to
> happen when recording and doing commercial detection.  It froze three times
> over three days and I started to worry.  I completely disabled commercial
> detection and it worked for two days straight so I decided to turn
> comflagging back on because the queue was huge.  It detected all the
> commercials in the recorded shows and the next day while recording and
> comflagging it died again!  So I turned off the realtime comflag option and
> it has been working for two days now without a hang.
>   I thought maybe it was a memory issue so I sacrificed a few shows and ran
> memtest86 overnight; it completed 12 cycles and didn't report any errors.
> None of the information I have proves anything but so far it's looking like
> some update done in may to the comflagger is the culprit.  Anyone have
> information that supports or debunks this theory?  It's not a big loss to
> not have realtime comflagging but it was a cool geek thing to tout. :)

If you have not made any hardware changes of any kind, or kernel changes 
recently Check the CPU temps, and check to make sure the cpu fan (and all other 
fans) are spinning, and check to make sure that the heat sink is not full of 
dust.     Any one of those will cause the machine under load to behave similar 
to what you describe, probably any other cpu intensive job will cause the 
machine to also hang.


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