I'm seeing a lot of this in my logs too - can anyone say exactly what this error means?
I'm running tvheadend version 3.1.694 on a raspberry pi (backend only - the pi is doing nothing else but running tvheadend) with a Tevii S660 USB tuner, streaming to VLC on my laptop.
If the issue is somehow due to lack of resources then I will try overclocking the pi, but I'd rather not do this unless I have to: tvheadend is using between 3% and 5% CPU while idle, 20-30% while streaming a clear SD channel and 30-40% while descrambling an SD channel.
Any suggestions please anyone?