Crash in Mythtv backend while deleting recording from web interface (port 6544)

[mythtv@…]

2016-02-28 00:42:12.744328 N  AutoExpire: CalcParams(): Max required Free Space: 52.0 GB w/freq: 14 min
2016-02-28 00:42:12.749932 N  Expiring 54 MB for 10004 at 2012-05-26T11:35:00Z => "Teleshop 4":Woningwijs
2016-02-28 00:42:12.753665 N  Expiring 2038 MB for 10002 at 2012-07-28T17:58:00Z => "NOS Journaal"
2016-02-28 00:42:12.757577 E  MainServer: ERROR when trying to delete file: myth://test-myth/10004_20120526133500.mpg. File doesn't exist.  Database metadata will not be removed.
2016-02-28 00:42:12.764945 E  MainServer: ERROR when trying to delete file: myth://test-myth/10002_20120728195800.mpg. File doesn't exist.  Database metadata will not be removed.
*** Error in `mythbackend': corrupted double-linked list: 0x93bb5310 ***
======= Backtrace: =========
/lib/libc.so.6(+0x77a1d)[0xb24e6a1d]
/lib/libc.so.6(+0x7900f)[0xb24e800f]
/usr/lib/libQt5Core.so.5(_ZN10QArrayData10deallocateEPS_jj+0x25)[0xb27e66c5]
/usr/lib/libQt5Core.so.5(+0x26a108)[0xb29c6108]
/usr/lib/libQt5Core.so.5(+0x260d68)[0xb29bcd68]
/usr/lib/libQt5Core.so.5(+0x2613c6)[0xb29bd3c6]
/usr/lib/libQt5Core.so.5(_ZNK14QFactoryLoader8instanceEi+0x31c)[0xb29b44ac]
/usr/lib/libQt5Gui.so.5(+0x12d7ff)[0xb316d7ff]
/usr/lib/libQt5Gui.so.5(_ZN12QImageWriter21supportedImageFormatsEv+0x2a0)[0xb316e290]
mythbackend[0x81e33f3]
/usr/local/lib/libmythservicecontracts-0.28.so.0(+0x1b53a)[0xb492a53a]
/usr/local/lib/libmythservicecontracts-0.28.so.0(_ZN15ContentServices11qt_metacallEN11QMetaObject4CallEiPPv+0x76)[0xb492acba]
mythbackend[0x820ca15]
/usr/local/lib/libmythupnp-0.28.so.0(_ZN10MethodInfo6InvokeEP7ServiceRK4QMapI7QStringS3_E+0x60d)[0xb534dd13]
/usr/local/lib/libmythupnp-0.28.so.0(_ZN11ServiceHost14ProcessRequestEP11HTTPRequest+0xe4b)[0xb534f999]
/usr/local/lib/libmythupnp-0.28.so.0(_ZN10HttpServer15DelegateRequestEP11HTTPRequest+0x296)[0xb53069e2]
/usr/local/lib/libmythupnp-0.28.so.0(+0x5fc30)[0xb5307c30]
/usr/local/lib/libmythbase-0.28.so.0(+0x3ab4d)[0xb50fbb4d]
/usr/local/lib/libmythbase-0.28.so.0(+0x37a29)[0xb50f8a29]
/usr/lib/libQt5Core.so.5(+0x890e5)[0xb27e50e5]
/lib/libpthread.so.0(+0x6955)[0xb2748955]
/lib/libc.so.6(clone+0x5e)[0xb255785e]

[Stuart Auchterlonie]

Moving unresolved tickets to next point release

[xtrab@…]

I just wanted to point out that the same thing happens when you try to delete a recording from either MythWeb or Web Frontend.

[stuartm]

Which version of QT? There is a known bug in one version which could explain this.

Otherwise we need a backtrace as described in the ticket how-to

[xtragb@…]

I am using Qt 5.6.0 on Arch linux. I suspected a Qt bug based on this error message in the kernel ring buffer:

"segfault at 10 ip 00007fe68048dd10 sp 00007fe57f7fcfd0 error 4 in libQt5Core.so.5.6.0[7fe680203000+4bf000]"

What's the last known working version of Qt?

[xtragb@…]

This problem seems to be related to GCC 6 and "some non-conforming code-bases" including Qt-5 as stated here ​https://gcc.gnu.org/gcc-6/changes.html. A workaround is to build Qt5 with the GCC flag -fno-delete-null-pointer-checks. This issue has been discussed on the Qt Development mailing list ​http://lists.qt-project.org/pipermail/development/2016-March/025153.html but it clearly has not been fixed as of the 5.6 release.

[Zoltán Karcagi <zkr@…>]

In c3a7929853026d98fb85bf76a79061d6b02f9b47/mythtv:

Error: Processor CommitTicketReference failed

GIT backend not available

[Stuart Auchterlonie]

Bill,

This appears related to #12782 which you are working on.

Regards Stuart

[Bill Meek]

OP:

Closing because the solution is likely being tracked in #12782. A true backtrace from gdb as requested earlier would confirm the issue. The original backtrace doesn't provide the necessary information. It does, however, reference QMetaObject. It doesn't have indexOfClassInfo in it, which is where the SEGV fires.

This is a good test:

curl --data RecordedId=12345 <backend>:6544/Dvr/DeleteRecording

The above works on 29-pre but drops core in 0.28. Just use a RecordedId that you don't have, no need to actually delete a recording. The a good response will be: false.

If the gdb output points to another method, then please reopen.