[mythtv] Deciphering backtrace of loop/segfault

Kevin Kuphal kkuphal at gmail.com
Tue Apr 6 18:06:25 UTC 2010


On Tue, Apr 6, 2010 at 12:17 PM, Robert McNamara
<robert.mcnamara at gmail.com> wrote:
> On Tue, Apr 6, 2010 at 10:08 AM, Kevin Kuphal <kkuphal at gmail.com> wrote:
>> On Tue, Apr 6, 2010 at 12:02 PM, Robert McNamara
>> <robert.mcnamara at gmail.com> wrote:
>>> On Tue, Apr 6, 2010 at 9:57 AM, Michael T. Dean <mtdean at thirdcontact.com> wrote:
>>>> On 04/06/2010 08:27 AM, Kevin Kuphal wrote:
>>>>>
>>>>> I have a friend who updated to 0.23-release tag from SVN and is
>>>>> experiencing the situation where his frontend segfaults when watching
>>>>> a recording.  I already had him clear out everything myth, distclean,
>>>>> recompile, etc. etc.  He compiled a debug copy of Myth and captured
>>>>> this backtrace.  Under gdb using the instructions on mythtv.org, the
>>>>> frontend doesn't segfault but sits at the "Please wait" screen.   Here
>>>>> is the results:
>>>>>
>>>>> http://pastebin.com/KXuaJGBY
>>>>>
>>>>> Any help would be greatly appreciated.
>>>>>
>>>>
>>>> Kevin,
>>>>
>>>> Though the backtrace doesn't tell me much (perhaps others can see more),
>>>> this sounds a lot like the the known race condition that "inspired"
>>>> http://svn.mythtv.org/trac/changeset/22350 as a workaround.  The real fix is
>>>> much more complex, and (TTBOMK), Mark K. will likely tackle it in the
>>>> libmythui-osd branch in order to allow the UI code and video code to be used
>>>> on the display at the same time.
>>>>
>>>> Does changing the 50ms sleep to some other value change the results?  If
>>>> not, I have another (more invasive) hack of a patch that changes timing more
>>>> significantly and can give you a copy to test as a system-specific
>>>> workaround.
>>>>
>>>> Mike
>>>
>>> This backtrace looks like someone has libmyth* junk left over from an
>>> old install.  did you have him rm /usr/lib/libmyth* and/or
>>> /usr/local/lib/libmyth*?
>>
>> I can have him clean that stuff out (I thought we had) but I know that
>> when I do a "ldd mythfrontend" that it only shows it linking against
>> the 0.23 libraries in the /usr/lib64 folder per our ./configure
>>
>> Kevin
>
> For what it's worth I tend to think that it's actually both the above
> and what Mike mentioned, I just know we've seen this same backtrace a
> couple times and in each case it was crufty leftovers that needed
> cleaning out in the lib dirs.  But one thing at a time, I guess.

Thanks guys.  It appears cleaning out the cruft did the trick.  I
thought he had done that.  Sorry for the noise.

Kevin


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