[mythtv-users] Problems with frontend crashing

[Tony Maro]

Alan Snyder wrote:

>--- Kevin <mythtv-users at simplyc.com> wrote:
>  
>
>I see the same problems, with live tv only, and have
>gdb running now to try to catch it.  I can fill in a
>lot of detail:
>
>- *Eventually* happens any time the frontend is left
>in live TV.  Could be 30 minutes, could be a day.
>
>- The picture and sound on the frontend freeze.
>
>- The frontend is still running, spitting out "Waited
>2 seconds for data to become available, waiting" every
>two seconds (this is in RingBuffer::ReadFromBuf in
>libs/libmythtv/RingBuffer.cpp).
>
>- Killing the frontend (killall works for me) and
>restarting restores things to normal.  The backend
>works throughout and doesn't produce any odd messages.
>
>- BUT I suspect a backend problem because Knoppmyth v4
>on a separate frontend machine did exactly the same
>thing.
>
>- There was some discussion in the past of this
>relating to a race condition.  Because my frontend
>usually hangs within several hours and now while
>running under gdb it's run without a hitch for a day,
>I wonder whether some timing subtlety is at fault. 
>(My live TV settings are adjusted to be sure I'm at
>80% or less CPU under gdb, and much less than that
>without gdb.)
>
>Any help would be greatly appreciated.  I would like
>to contribute more but my understanding of the code is
>limited and this one seems to be rather subtle.  We
>almost exclusively use our myth box for recording
>right now.  This problem is preventing me from moving
>ahead with a kitchen installation for my wife that
>would use live tv pretty heavily.
>
>___________________________
>
I'll add this - my remote control problem is related to transcode in the 
background.  Apparently the irxevent isn't getting enough processor 
cycles to accurately interpret my raw IR signals.

I have also noticed I can force a crash by starting live TV and then 
uploading a DIVX file across the network from another machine... 
increasing the workstation load and network traffic.  Last night my 
daughter was watching live TV, and I went to my workstation and uploaded 
a ripped DVD.  I walked back in the living room and asked how the remote 
was working and she said "it's not working well now" and then all of a 
sudden the frontend froze. 

I fixed the irxevent problem by starting it with "sudo nice --14 
irxevent &" (I added my mythtv user to the sudo list for nice.)

It seems to only happen when the frontend is at the end of the stream.  
If I watch TV a few minutes behind live stream, it doesn't seem to do 
this.  Perhaps the frontend is trying to auto-correct frame speed to a 
point that's beyond the real current stream?  Having a 99% load while 
transcoding seems to make it more likely to happen.  Having heavy 
network traffic almost guarantees it.

-Tony