Sf2 Player segfaults when trying to play note while still loading

### Bug Summary

Hitting a note while the Sf2 Player plugin is still loading the default font file results in an immediate segfault.

#### Steps to reproduce

Read all steps before trying.

1. Get a large .sf2 soundfont. In my case I converted [`MS Basic.sf3` delivered with MuseScore](https://github.com/musescore/MuseScore/tree/cd7979283bc5b7845b9052c57c7f8814e2419dc2/share/sound) to an .sf2 using [polyphone](https://www.polyphone-soundfonts.com/), which resulted in an 467 MiB large file
2. Open LMMS with an empty project, and set that soundfont as default
3. In **quick succession**,
1. Add a Sf2 Player to the Song-Editor, which will show up as `Default preset` at first
2. Open its settings by clicking on `Default preset`
3. Hit any note through keyboard (e.g. y on a QWERTY keyboard) or mouse on the displayed keyboard

#### Expected behavior

To have the input ignored until it's fully loaded.

#### Actual behavior

LMMS as a whole segfaults. Backtrace below in logs.

#### Affected LMMS versions

- 1.2.2 [from nixpkgs](https://github.com/NixOS/nixpkgs/blob/0c19eb6916ade1024700a42ef72ba69656053f3c/pkgs/applications/audio/lmms/default.nix) (which just built from the `v1.2.2` tag)

Couldn't test master since I was unable to drag _any_ instrument into any panel there, which is likely another issue. I'm not sure if I should report another issue at all for this.

#### System Info

- OS: NixOS 23.05 (Linux distro)
- WM: Sway (Wayland)

#### Logs

Click to expand
(Thread 1 at the bottom might be the most relevant.)

Core was generated by `lmms'.

Program terminated with signal SIGSEGV, Segmentation fault.

#0  0x000000000054cc13 in NotePlayHandle::NotePlayHandle(InstrumentTrack*, int, int, Note const&, NotePlayHandle*, int, NotePlayHandle::Origins) ()

[Current thread is 1 (Thread 0x7f4e9c021d00 (LWP 33276))]

(gdb) thread apply all bt


Thread 27 (Thread 0x7f4e37fff6c0 (LWP 33297)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 26 (Thread 0x7f4e85c9b6c0 (LWP 33280)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 25 (Thread 0x7f4e355706c0 (LWP 33301)):

#0  0x00007f4e9cb1477f in poll () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x000000000058ed23 in MidiAlsaSeq::run() ()

#2  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#4  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 24 (Thread 0x7f4e54ff96c0 (LWP 33296)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 23 (Thread 0x7f4e1af706c0 (LWP 33303)):

#0  0x00007f4e9cb1074c in read () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca975a8 in __GI__IO_file_xsgetn () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9ca8b97f in fread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#3  0x00007f4e87b485a9 in safe_fread () from /nix/store/582jfgrjj120xbz6khcv4aniq2vpb31w-fluidsynth-2.3.2/lib/libfluidsynth.so.3

#4  0x00007f4e87b495e8 in fluid_sffile_read_sample_data () from /nix/store/582jfgrjj120xbz6khcv4aniq2vpb31w-fluidsynth-2.3.2/lib/libfluidsynth.so.3

#5  0x00007f4e87b4c3f9 in fluid_samplecache_load () from /nix/store/582jfgrjj120xbz6khcv4aniq2vpb31w-fluidsynth-2.3.2/lib/libfluidsynth.so.3

#6  0x00007f4e87b46b66 in fluid_defsfont_load_all_sampledata () from /nix/store/582jfgrjj120xbz6khcv4aniq2vpb31w-fluidsynth-2.3.2/lib/libfluidsynth.so.3

--Type  for more, q to quit, c to continue without paging--c

#7  0x00007f4e87b480cb in fluid_defsfont_load () from /nix/store/582jfgrjj120xbz6khcv4aniq2vpb31w-fluidsynth-2.3.2/lib/libfluidsynth.so.3

#8  0x00007f4e87b481ba in fluid_defsfloader_load () from /nix/store/582jfgrjj120xbz6khcv4aniq2vpb31w-fluidsynth-2.3.2/lib/libfluidsynth.so.3

#9  0x00007f4e87b5eb5d in fluid_synth_sfload () from /nix/store/582jfgrjj120xbz6khcv4aniq2vpb31w-fluidsynth-2.3.2/lib/libfluidsynth.so.3

#10 0x00007f4e87fd75ea in sf2Instrument::openFile(QString const&, bool) () from /nix/store/q3w6gzzfgfsjpqznir39fg8bb6piv4a9-lmms-1.2.2/lib/lmms/libsf2player.so

#11 0x00007f4e87fd8666 in sf2Instrument::loadFile(QString const&) () from /nix/store/q3w6gzzfgfsjpqznir39fg8bb6piv4a9-lmms-1.2.2/lib/lmms/libsf2player.so

#12 0x00007f4e87fd9093 in sf2Instrument::sf2Instrument(InstrumentTrack*) () from /nix/store/q3w6gzzfgfsjpqznir39fg8bb6piv4a9-lmms-1.2.2/lib/lmms/libsf2player.so

#13 0x00007f4e87fd9471 in lmms_plugin_main () from /nix/store/q3w6gzzfgfsjpqznir39fg8bb6piv4a9-lmms-1.2.2/lib/lmms/libsf2player.so

#14 0x00000000005549d6 in Plugin::instantiate(QString const&, Model*, void*) ()

#15 0x0000000000527385 in Instrument::instantiate(QString const&, InstrumentTrack*) ()

#16 0x000000000064ce66 in InstrumentTrack::loadInstrument(QString const&) ()

#17 0x00000000005e80f4 in InstrumentLoaderThread::run() ()

#18 0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#19 0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#20 0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 22 (Thread 0x7f4e7affd6c0 (LWP 33285)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 21 (Thread 0x7f4e7bfff6c0 (LWP 33283)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 20 (Thread 0x7f4e55ffb6c0 (LWP 33294)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 19 (Thread 0x7f4e567fc6c0 (LWP 33293)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 18 (Thread 0x7f4e35d716c0 (LWP 33300)):

#0  0x00007f4e9cb14876 in ppoll () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9e0c7079 in pa_mainloop_poll () from /nix/store/6bib656mdj343lhimh6f7fccc3bx33mb-libpulseaudio-16.1/lib/libpulse.so.0

#2  0x00007f4e9e0c7656 in pa_mainloop_iterate () from /nix/store/6bib656mdj343lhimh6f7fccc3bx33mb-libpulseaudio-16.1/lib/libpulse.so.0

#3  0x00007f4e9e926b3d in PULSE_WaitAudio () from /nix/store/vnlvsfajwhkdbz0bi0s9s3c8q0vnnh61-SDL-1.2.15/lib/libSDL-1.2.so.0

#4  0x00007f4e9e8fc453 in SDL_RunAudio () from /nix/store/vnlvsfajwhkdbz0bi0s9s3c8q0vnnh61-SDL-1.2.15/lib/libSDL-1.2.so.0

#5  0x00007f4e9e904a68 in SDL_RunThread () from /nix/store/vnlvsfajwhkdbz0bi0s9s3c8q0vnnh61-SDL-1.2.15/lib/libSDL-1.2.so.0

#6  0x00007f4e9e941db9 in RunThread () from /nix/store/vnlvsfajwhkdbz0bi0s9s3c8q0vnnh61-SDL-1.2.15/lib/libSDL-1.2.so.0

#7  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#8  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 17 (Thread 0x7f4e79ffb6c0 (LWP 33287)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 16 (Thread 0x7f4e1bfff6c0 (LWP 33302)):

#0  0x00007f4e9cb19d8d in syscall () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9d0d7b9b in QSemaphore::acquire(int) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#2  0x0000000000545cbc in Mixer::fifoWriter::write(float (*) [2]) ()

#3  0x0000000000547a5d in Mixer::fifoWriter::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 15 (Thread 0x7f4e797fa6c0 (LWP 33288)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 14 (Thread 0x7f4e377fe6c0 (LWP 33298)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 13 (Thread 0x7f4e557fa6c0 (LWP 33295)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 12 (Thread 0x7f4e8549a6c0 (LWP 33281)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 11 (Thread 0x7f4e577fe6c0 (LWP 33291)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 10 (Thread 0x7f4e56ffd6c0 (LWP 33292)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 9 (Thread 0x7f4e78ff96c0 (LWP 33289)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 8 (Thread 0x7f4e57fff6c0 (LWP 33290)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 7 (Thread 0x7f4e7b7fe6c0 (LWP 33284)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 6 (Thread 0x7f4e84c996c0 (LWP 33282)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 5 (Thread 0x7f4e8d9fe6c0 (LWP 33279)):

#0  0x00007f4e9cb1477f in poll () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9979cae1 in QtWaylandClient::EventThread::run() () from /nix/store/hns13dyj67wv6xz4qfk4xvfrig3fq2zi-qtwayland-5.15.10/lib/libQt5WaylandClient.so.5

#2  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#4  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 4 (Thread 0x7f4e7a7fc6c0 (LWP 33286)):

#0  0x00007f4e9ca9ca36 in __futex_abstimed_wait_common () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9ca9f228 in pthread_cond_wait@@GLIBC_2.3.2 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#2  0x00007f4e9d0dba3b in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x0000000000549789 in MixerWorkerThread::run() ()

#4  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#6  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 3 (Thread 0x7f4e8e1ff6c0 (LWP 33278)):

#0  0x00007f4e9cb1477f in poll () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9979cae1 in QtWaylandClient::EventThread::run() () from /nix/store/hns13dyj67wv6xz4qfk4xvfrig3fq2zi-qtwayland-5.15.10/lib/libQt5WaylandClient.so.5

#2  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#3  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#4  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 2 (Thread 0x7f4e992b06c0 (LWP 33277)):

#0  0x00007f4e9cb1477f in poll () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#1  0x00007f4e9bd16fde in g_main_context_iterate.constprop () from /nix/store/4vrk6zldfblhry2hi4p0jsy4j7nsvgaz-glib-2.76.2/lib/libglib-2.0.so.0

#2  0x00007f4e9bd170fc in g_main_context_iteration () from /nix/store/4vrk6zldfblhry2hi4p0jsy4j7nsvgaz-glib-2.76.2/lib/libglib-2.0.so.0

#3  0x00007f4e9d324786 in QEventDispatcherGlib::processEvents(QFlags) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#4  0x00007f4e9d2cadc3 in QEventLoop::exec(QFlags) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#5  0x00007f4e9d0d4757 in QThread::exec() () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#6  0x00007f4e99387767 in QDBusConnectionManager::run() () from /nix/store/lw4567l5nr4x9bkqm5ficg888a0ns5wc-qtwayland-5.15.10-bin/lib/qt-5.15.10/plugins/platforms/../../../../../n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5DBus.so.5

#7  0x00007f4e9d0d5b2c in QThreadPrivate::start(void*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#8  0x00007f4e9ca9fe24 in start_thread () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

#9  0x00007f4e9cb219b0 in clone3 () from /nix/store/46m4xx889wlhsdj72j38fnlyyvvvvbyb-glibc-2.37-8/lib/libc.so.6

Thread 1 (Thread 0x7f4e9c021d00 (LWP 33276)):

#0  0x000000000054cc13 in NotePlayHandle::NotePlayHandle(InstrumentTrack*, int, int, Note const&, NotePlayHandle*, int, NotePlayHandle::Origins) ()

#1  0x000000000054cd6e in NotePlayHandleManager::acquire(InstrumentTrack*, int, int, Note const&, NotePlayHandle*, int, NotePlayHandle::Origins) ()

#2  0x000000000065022a in InstrumentTrack::processInEvent(MidiEvent const&, MidiTime const&, int) [clone .part.0] ()

#3  0x00000000005d4a6c in PianoView::mousePressEvent(QMouseEvent*) ()

#4  0x00007f4e9e3b2f18 in QWidget::event(QEvent*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Widgets.so.5

#5  0x00007f4e9e370fde in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Widgets.so.5

#6  0x00007f4e9e37951d in QApplication::notify(QObject*, QEvent*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Widgets.so.5

#7  0x00007f4e9d2cc3c8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#8  0x00007f4e9e37762e in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer&, bool, bool) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Widgets.so.5

#9  0x00007f4e9e3cbd4e in QWidgetWindow::handleMouseEvent(QMouseEvent*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Widgets.so.5

#10 0x00007f4e9e3cf1f0 in QWidgetWindow::event(QEvent*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Widgets.so.5

#11 0x00007f4e9e370fde in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Widgets.so.5

#12 0x00007f4e9d2cc3c8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#13 0x00007f4e9d7303fd in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Gui.so.5

#14 0x00007f4e9d70333c in QWindowSystemInterface::sendWindowSystemEvents(QFlags) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Gui.so.5

#15 0x00007f4e997d31c0 in userEventSourceDispatch(_GSource*, int (*)(void*), void*) () from /nix/store/hns13dyj67wv6xz4qfk4xvfrig3fq2zi-qtwayland-5.15.10/lib/libQt5WaylandClient.so.5

#16 0x00007f4e9bd16dbd in g_main_context_dispatch () from /nix/store/4vrk6zldfblhry2hi4p0jsy4j7nsvgaz-glib-2.76.2/lib/libglib-2.0.so.0

#17 0x00007f4e9bd17068 in g_main_context_iterate.constprop () from /nix/store/4vrk6zldfblhry2hi4p0jsy4j7nsvgaz-glib-2.76.2/lib/libglib-2.0.so.0

#18 0x00007f4e9bd170fc in g_main_context_iteration () from /nix/store/4vrk6zldfblhry2hi4p0jsy4j7nsvgaz-glib-2.76.2/lib/libglib-2.0.so.0

#19 0x00007f4e9d324786 in QEventDispatcherGlib::processEvents(QFlags) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#20 0x00007f4e9d2cadc3 in QEventLoop::exec(QFlags) () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#21 0x00007f4e9d2d32c6 in QCoreApplication::exec() () from /nix/store/n737h1wk1wkfjw6v7f9figyx6vwn6ns2-qtbase-5.15.10/lib/libQt5Core.so.5

#22 0x00000000004c4b01 in main ()

Reproduce with a large .sf2 file while following the loading sequence, then inspect the backtrace around NotePlayHandle::NotePlayHandle and sf2Instrument::openFile/loadFile. Read the loading path through InstrumentLoaderThread and the Sf2 Player implementation. Done means triggering notes during loading no longer segfaults and input is ignored until loading completes.

Written by the indexing model from the issue text.