[mythtv] mythbackend spinning in "Waiting for a thread ..."

Robert Tsai rtsai1111 at comcast.net
Thu Jun 16 16:24:55 UTC 2005

On Thu, Jun 16, 2005 at 11:21:08AM -0400, Isaac Richards wrote:
> On Thursday 16 June 2005 09:47 am, Robert Tsai wrote:
> > I am going to blindly hypothesize that this might be related to
> > the AMD64-specific pthreads problem for which exists Kyle's
> > workaround in RingBuffer, but there don't appear to be any
> > readwrite locks involved in this bit of the code (although I'm not
> > familiar with QMutex).
> Actually, it's quite possibly to be the same issue, if mythweb is
> requesting the backend to generate thumbnails for the recordings.
> That will involve the RingBuffer class (to read the local video
> file), and if enough of those queries stack up due to problems
> there, you'd see the current behaviour.

But I already have Kyle's RingBuffer patch applied, so if it's just
re-using RingBuffer code, then it shouldn't be this exactly same
issue, right?

> It shouldn't be terribly hard to get a backtrace of the backend in
> its stuck state - it'd be interesting to see where the threads are.

Anyway, yeah, I'll debug later. I don't know about getting an "all
threads" backtrace, though. I tried that, and I had some threads that
had call stacks of 1000 frames and counting (had to kill gdb).

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