[mythtv-users] ringbuffer errors?

[Mark Perkins]

> On 2 Jan 2014, at 3:28 am, "Rich West" <Rich.West at wesmo.com> wrote:
> 
> Of course, MythTV decides to act up last night.. to the point where watching
> a recording of the ball dropping was just not possible (I heard a LOT of "I
> think this is the year we move away from mythtv!" from my other half).
> 
> The story goes that we set up ~5hrs of recording of one particular channel
> to make sure we were able to watch the entire evening's worth of events (we
> decided not to use livetv since that is sketchy to start with).  I canceled
> all other recordings from 8pm through to 3am, so the only thing the backend
> had to do was record and stream.  I even killed off the real-time commercial
> flagger.
> 
> The symptoms we saw were the "Please wait..." black screen for >90 seconds
> before it would start playing.  Skipping forward to near real time would
> cause the video/audio to stop playing, and mythfrontend would become
> unresponsive for a LONG time, eventually exiting the stream with a complaint
> about the video buffers.  Going through that same process again, but not
> skipping to real time did work, but it would randomly barf out again with
> the same problem
> 
> The logs on the backend were showing the following ONLY when the frontend
> was attempting to access the video.  Google searches show up similar errors
> with varying resolutions (someone re-cabled the video cables for their
> settop boxes, another re-formatted their drives, and yet another replaced
> their drives.. the 'solutions' seemed unusually random):
> 2014-01-01 00:00:11.686894 I [1149/2045] ProcessRequest ringbuffer.cpp:1098
> (WaitForAvail) - RingBuf(/video/1006_20140101030000.mpg): Waited 0.2 seconds
> for data
>                        to become available... 239926 < 753664
> 
> CPU usage & network usage on both the frontend and backend systems were
> extremely low.  From that standpoint, they were basically bored.  Disk I/O
> seemed fine (of course sysstat wasn't installed, and there was essentially a
> revolt, so I couldn't dig too deep with the debugging), no disk errors
> reported, and generally the backend appeared healthy (I graph everything via
> cacti, including tuner usage, jobs, errors, etc).  I've never had issues
> like this in the past, and we essentially did the same thing around
> Thanksgiving (family over likes the football games) with great success. 
> Needless to say, it was very frustrating, and I'm not sure where to even
> begin looking..
> 
> -Rich
> 
> 
> 
> _______________________________________________
What version mythtv are you running? If I remember correctly I used to get large numbers of those messages in my logs in 0.26/fixes but with no playback problems. I think they disappeared in the logs in 0.27, not because they stopped happening but because they were removed from the default log level. At least I think that's how I remember it - I can't quite recall at the moment.

Long story short I don't think the ringbuffer message is necessarily a symptom of your problem. Or a problem causing your symptom, whichever is applicable. I assume 0.2sec would essentially be unnoticeable anyway, if it was waiting several seconds might be a different story?