Bug 482335

Summary:	kioworker crashes while creating MLT thumbnail
Product:	[Applications] kdenlive	Reporter:	Angkun-ane "Diskette" Khunpradith <diskette>
Component:	Setup & Installation	Assignee:	Jean-Baptiste Mardelle <jb>
Status:	RESOLVED FIXED
Severity:	crash	CC:	kdelibs-bugs, Landgraf132, nicolas.fella, saileshpoudel0
Priority:	NOR	Keywords:	qt6
Version:	24.02.0
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:	https://invent.kde.org/multimedia/kdenlive/-/commit/ca01d111e8868e2657e7271ea58ae1469a1b8e34	Version Fixed In:	24.02.1
Sentry Crash Report:
Attachments:	a gdb debug log of kioworker crashing

Description Angkun-ane "Diskette" Khunpradith 2024-03-03 18:21:05 UTC

Created attachment 166368 [details]
a gdb debug log of kioworker crashing

SUMMARY
When I move files or do something that changes the thumbnail or generate a new one, kioworker will sometimes crash.
Or randomly crashes entirely and I don't know why.
***
NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports
***


STEPS TO REPRODUCE
1. Try moving files, or something that has to do with regenerating a thumbnail

OBSERVED RESULT
kioworker crashed

EXPECTED RESULT
kioworker not crashing

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Arch Linux
(available in About System)
KDE Plasma Version: 6.0.0
KDE Frameworks Version:  6.0.0
Qt Version: 6.7.0

ADDITIONAL INFORMATION
My Arch Linux installation has testing and kde-unstable repositories enabled.

Comment 1 Nicolas Fella 2024-03-03 18:44:21 UTC

What seems to happen is:

- A thumbnail for a kdenlive file is requested
- The mltthumbnailer (build against Qt6) is activated
- At some point that loads libmltqt.so and creates a QApplication
- libmltqt.so is built against Qt5
- Now we are mixing Qt5 and Qt6 in the same process, which causes problems

Not sure whether it's expected that the mlt thumbnailer creates/needs a QApplication. But it looks like a packaging issue that MLT with Qt5 is used with Qt6 Kdenlive

Comment 2 Nicolas Fella 2024-03-07 10:17:43 UTC

*** Bug 482631 has been marked as a duplicate of this bug. ***

Comment 3 Bug Janitor Service 2024-03-07 13:03:37 UTC

A possibly relevant merge request was started @ https://invent.kde.org/multimedia/kdenlive/-/merge_requests/472

Comment 4 Antonio Rojas 2024-03-07 16:16:56 UTC

Git commit 56cb0ef567cacf4a87964cd51a53371fbc109470 by Antonio Rojas.
Committed on 07/03/2024 at 13:00.
Pushed by nicolasfella into branch 'master'.

Block Qt5 MLT plugins in thumbnailer when building with Qt6.

Follow up to a3d52b2b3258a9c250dd3ad27d618d024beee4c6

M  +5    -0    thumbnailer/mltpreview.cpp

https://invent.kde.org/multimedia/kdenlive/-/commit/56cb0ef567cacf4a87964cd51a53371fbc109470

Comment 5 Nicolas Fella 2024-03-07 16:17:32 UTC

Git commit ca01d111e8868e2657e7271ea58ae1469a1b8e34 by Nicolas Fella, on behalf of Antonio Rojas.
Committed on 07/03/2024 at 16:17.
Pushed by nicolasfella into branch 'release/24.02'.

Block Qt5 MLT plugins in thumbnailer when building with Qt6.

Follow up to a3d52b2b3258a9c250dd3ad27d618d024beee4c6
(cherry picked from commit 56cb0ef567cacf4a87964cd51a53371fbc109470)

M  +5    -0    thumbnailer/mltpreview.cpp

https://invent.kde.org/multimedia/kdenlive/-/commit/ca01d111e8868e2657e7271ea58ae1469a1b8e34