[mythtv-users] latest 0.26: segfault in BE

[Jonatan Lindblad]

On 2012-10-02 18:45, Steven Adeff wrote:
> On Tue, Oct 2, 2012 at 4:27 AM, warpme<warpme at o2.pl>  wrote:
>> Hi,
>>
>> I get this segfault during LiveTV channel change.
>> Unfortunately I don't have trace.
>> Generally, getting trace will be quite difficult as my sys is very stable
>> (24/7 operation with 50-70 recordings per day; last segfault in BE was 5-6
>> month ago), so I don't want to run BE under gdb for another half of year.
>>
>> Taking into account info available in below dump, should I:
>>
>> -hope devs will find time and look on below info
>> -create ticket for it
>> -forget about it as below info is not sufficient to attack problem
>>
>> -br
>>
>>
>> 2012-10-02 07:33:40.337745 I TVRec(17): Changing from WatchingLiveTV to None
>> 2012-10-02 07:33:40.364897 I DVBSM(/dev/dvb/adapter8/frontend0): Signal
>> Locked *** glibc detected *** /usr/bin/mythbackend: double free or
>> corruption (out): 0x00007fa5f8d35400 *** ======= Backtrace: =========
>> /lib/libc.so.6(+0x78a56)[0x7fa689fc9a56]
>> /usr/lib/libmythtv-0.26.so.0(_ZN11LiveTVChainD1Ev+0x31)[0x7fa68dec2157]
>> 2012-10-02 07:33:40.626595 I TVRec(17):
>> FinishedRecording(8035_2012-10-02T05:33:33Z) damaged recq:<RecordingQuality
>> overall_score="0" key="23809_2012-10-02T05:33:17Z"
>> countinuity_error_count="0" packet_count="131257">  <Gap
>> start="2012-10-02T05:25:00Z" end="2012-10-02T05:33:17Z" duration="497" />
>> <Gap start="2012-10-02T05:33:30Z" end="2012-10-02T06:00:00Z" duration="1589"
>> />  </RecordingQuality>  /usr/bin/mythbackend[0x494158]
>> /usr/bin/mythbackend[0x492e1a]
>> /usr/lib/libmythbase-0.26.so.0(_ZN10MythSocket5closeEv+0x205)[0x7fa68d609a6b]
>> /usr/lib/libmythbase-0.26.so.0(_ZN13MSocketDevice9writeDataEPKcx+0x4a6)[0x7fa68d70cec2]
>> /usr/lib/libQtCore.so.4(_ZN9QIODevice5writeEPKcx+0xb4)[0x7fa68ac0a114]
>> /usr/lib/libmythbase-0.26.so.0(+0x59121)[0x7fa68d614121]
>> /usr/lib/libmythbase-0.26.so.0(_ZN10MythSocket10writeBlockEPKcy+0x4c6)[0x7fa68d60a754]
>> /usr/lib/libmythbase-0.26.so.0(_ZN10MythSocket15writeStringListER11QStringList+0xf5a)[0x7fa68d60b9a4]
>> /usr/bin/mythbackend[0x46c62c] /usr/bin/mythbackend[0x482356]
>> /usr/bin/mythbackend[0x461c42] /usr/bin/mythbackend[0x460854]
>> /usr/bin/mythbackend[0x4991fd]
>> /usr/lib/libmythbase-0.26.so.0(+0x490ba)[0x7fa68d6040ba]
>> /usr/lib/libmythbase-0.26.so.0(+0x4623f)[0x7fa68d60123f]
>> /usr/lib/libQtCore.so.4(+0x7b68b)[0x7fa68ab7b68b]
>> /lib/libpthread.so.0(+0x7e0e)[0x7fa68c8cde0e]
>> /lib/libc.so.6(clone+0x6d)[0x7fa68a0351ed]

You should be able to find out what the addresses from mythbackend point 
out by running for example
addr2line -e /usr/bin/mythbackend 0x494158

though I think it's crashing in MainServer::DeleteChain() called from 
MainServer::connectionClosed().

> you can attach to an existing session,
> http://www.mythtv.org/wiki/Debugging#Attaching_gdb_to_a_running_process

That's useful if it's easy to reproduce, otherwise it's better to use 
core files, http://www.mythtv.org/wiki/Debugging#Using_core_files.

--
Jonatan