[mythtv] Ticket #2817: Unknown problem with socket communications causes segfault of backends

[Mark Buechler]

Ok, after looking at the code a bit more last night I had a thought about
MainServer::customEvent() around the end where the iterator gets set back to
the first entry in the list:

            if (sock->DownRef())
            {
                // was deleted elsewhere, so the iterator's invalid.
                iter = playbackList.begin();
            }

What exactly does this protect against? Is it possible for two threads to
think each other has deleted entries in the list and reset their iterators
when in fact neither one has? Can this be fixed with a mutex lock?

- Mark.

On 1/8/07, Mark Buechler <mark.buechler at gmail.com> wrote:
>
> I added some code around line 804 of mainserver.cpp to spit out the
> QStringList entries as well as "broadcast" and the backend runs fine to a
> point then send RECORDING_LIST_CHANGE hundreds of times a second for several
> seconds and eventually starts sending SCHEDULE_CHANGE as well. Eventually
> DONE_RECORDING starts getting sent as well as LIVETV_CHAIN. So, looks like
> to me there's a queue which isn't getting cleared.
>
> - Mark.
>
> On 1/8/07, Martin Møller <martin at martinm-76.dk> wrote:
> >
> > I have made a backtrace of mythbackend today as well. It seems to be the
> > ProcessRequestWork bug that got me...
> >
> > I'll upload it to this ticket in the hope that it will enlighten someone
> > :)
> >
> > I'm running revision 12434 at the moment...
> >
> > /Martin.
> >
> > ----- Mark Buechler <mark.buechler at gmail.com> wrote:
> > > Has anyone had time to look at this? Looking at the bt's, there seems
> > > to be two bugs, but by far the biggest is the one involving MythEvent
> > > - specifically the QValueList extradata on sending in
> > > MainServer::customEvent() and at times the receiving of QStringLists
> > > in MainServer::ProcessRequestWork(). I've looked at the code for
> > > obvious problems (like extradata not getting initialized before being
> > > added to the "broadcast" QValueList), but nothing pops out at me. This
> > > bug causes my two backends to crash once every day or two.
> > >
> > > - Mark.
> > >
> > >
> > > On 12/25/06 , MythTV < mythtv at cvs.mythtv.org > wrote: #2817: Unknown
> > > problem with socket communications causes segfault of backends
> >
> > _______________________________________________
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> >
>
>
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