Bug 448684

SUMMARY
Upon quitting KDevelop normally (Alt+F4 or closing the window), the window closes, but a `kdevelop` process is left in the background. The process would hog a single thread/CPU core with 100% usage, and it doesn't go away. No errors are thrown and no crashes occur. This is reproducible on every launch and exit of KDevelop. Clearing `~/.cache/kdevduchain` or `~.cache/kdevelop` doesn't change the outcome. Running it with `strace` doesn't show anything useful and running it in the console doesn't show anything either. 


STEPS TO REPRODUCE
1. Launch KDevelop
2. Quit KDevelop (doesn't matter if a session is chosen or not).

OBSERVED RESULT
KDevelop doesn't terminate and must be forcefully killed with 'kill -9'. The process hogs the CPU thread or core and upon relaunch (if the process is still active), the new KDevelop instance would complain about a session already being active.

EXPECTED RESULT
KDevelop's processes terminate normally. No zombie or background processes left behind.

ADDITIONAL INFORMATION:
I would like to think this was a regression, as this problem didn't occur in previous versions (IIRC). I do not recall having this problem two months ago.

SOFTWARE/OS VERSIONS
Operating System: openSUSE Leap 15.3
KDE Plasma Version: 5.23.5
KDE Frameworks Version: 5.90.0
Qt Version: 5.15.2
Kernel Version: 5.3.18-59.37-default (64-bit)
Graphics Platform: X11
Processors: 4 × Intel® Core™ i5-3320M CPU @ 2.60GHz
Memory: 7.6 GiB of RAM
Graphics Processor: Mesa DRI Intel® HD Graphics 4000