[mythtv-users] Best way to submit debug data for Mythbuntu 0.24 autobuilds

[James Crow]

On Mon, Oct 11, 2010 at 12:53 PM, Michael T. Dean
<mtdean at thirdcontact.com> wrote:
>  On 10/11/2010 08:09 AM, James Crow wrote:
>>
>> I have been running Mythbuntu 10.04 w/ 0.24 autbuilds for a few weeks.
>> A couple of times a week my MBE locks up. It does not segfault, it
>> just stops responding to any FE and the current recordings on the MBE
>> stop as well. The problem always occurs just as a show is starting to
>> record. I want to make sure I get the required debugging data to
>> submit a ticket.
>>
>> I have the mythtv-dbg build installed. I think I will need to run
>> mythbackend under gdb as per the documentation. On Mythbuntu the BE is
>> normally run as user mythtv. Should I alter the upstart script to make
>> mythbackend run under gdb? Should I start gdb/mythbackend from a
>> normal shell and wait for the lockup to Ctrl-C the gdb process? I
>> think the documentation is describing a situation where the BE seg
>> faults rather than just locks up. Any ideas of the proper way to
>> generate a backtrace under these circumstances is appreciated.
>
> Another option is to run mythbackend normally, then attach gdb to the
> running (and locked up) process, as at
>
> http://sourceware.org/gdb/download/onlinedocs/gdb/Attach.html#Attach
>
> Find the process ID for the appropriate mythbackend process (remember that
> in 0.23-fixes and below, some mythbackend processes are used to generate
> previews, so you will likely want to use the oldest of the processes).
>
> ps -efw | grep mythback
>
> Once you know the process ID, start gdb and submit the commands:
>
> handle SIGPIPE nostop noprint
> handle SIG33 nostop noprint
> set logging on
> set pagination off
> set breakpoint pending on
> break qFatal
> thread apply all bt full
>
> and once you've gotten the information you need,
>
> set logging off
>
> Once you've been through the process, free to clean up the instructions (and
> fix any incorrect info I put in) and add a new section 4 to:
>  http://www.mythtv.org/wiki/Debugging
>
> Thanks,
> Mike
>
> (Yeah, some of those commands aren't necessary, but they won't hurt and I
> figured it's better to make generic instructions that would allow anyone to
> use this approach--even if their backend isn't locked up or whatever, and
> they planned to continue running under gdb.)

Excellent. Now all I have to do is what for mythbackend to lockup
again. :) The only catch is it normally happens at 8PM just as the
primetime shows start to record. Maybe I should setup some throwaway
recordings so that all recorders start simultaneously to test.

Thanks,
James