Linux user researching issue with important software

gandsnut

My "daily-driver" computer runs Ubuntu 20.04 with multiple user desktop choices (KDE/Plasma, Budgie, Gnome & MATE, XFCE4).
The software I deem important is a cross-platform free application 'MuseScore' (MS). MS is a music notation & playback software.
Based on info from the program itself, it uses Qt 5.9.8 version.

I'm experiencing deteriorating MS GUI response, seen over the last 2 or so months. Certain program pop-up windows can send the program into a 'freeze' situation, where one (of four) CPU cores goes 100% -- for upwards of 100 seconds (!). I'm trying to understand my Ubuntu version + whatever Qt is 'running' on my system + how the various desktops impact the issue of MS responsiveness. I'm struggling to find WHAT Qt version is active, and if different versions apply (or are used) by different desktops.

Any suggestions / help is appreciated.

jsulm

@gandsnut How did you install this application? Does it provide Qt libraries it uses or does it use preinstalled Qt libraries (provided by Ubuntu)?

gandsnut

@jsulm MS for Linux can be 1) installed or use 2) AppImage binary. I use the latter for all 3 versions of MS (3.6.2 / 3.7 development / 4.0.x newest). The screen cap I provided is from the 3.6.2 version.

(Eventually MS4.x will mature and I may start using that version, but that's probably 6 months down the road. I don't give any importance to how the current MS4 behaves, because it is so new a release.)

I doubt the MS software provides anything Qt, even if I were to choose an INSTALL rather than using AppImages. So I bet it uses whatever Qt component that prevails on Ubuntu.

jsulm

@gandsnut said in Linux user researching issue with important software:

So I bet it uses whatever Qt component that prevails on Ubuntu.

I don't think so. If you're using AppImage version then it already contains everything (including Qt libraries) needed to run the application.

Kent-Dorfman

FWIW,

ldd {qt-application}

then do a dpkg -S library.so for some library presented by the previous command. That will tell you what debian/screwbuntu package owns the library being used for the application.

then apt list {pkgname} and search for "installed"

gandsnut

@Kent-Dorfman

It looks like there are 91 items listed from the 'ldd' command. Some appear "brought in" with the executable, others appear utilized from the OS. I picked a few lines to show here:

libQt5Core.so.5 => /tmp/.mount_musesc0ALcN2/bin/./../lib/libQt5Core.so.5 (0x00007fe05d6db000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fe05d4f9000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fe05d4de000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fe05d2ec000)
libvorbis.so.0 => /tmp/.mount_musesc0ALcN2/bin/./../lib/libvorbis.so.0 (0x00007fe05d0c0000)

The lines that begin with "/tmp/mount_...." are found in a /tmp directory that appears ONLY when the MuseScore program is running.

Not sure what to make of this or what to investigate further. Thanks.

Kent-Dorfman

@gandsnut
Ok. so it looks like whatever MS app is is pulling in its own versions of system libraries instead of using the default ones. Maybe its time to go to the application support channel for that tool. It's not a Qt specific question at this point.