QApplication & QThread issues when forking multiple xterms and ipdb

for ‘ages’ I have been using a standard procedure to debug apps on Suse, developed using MPI and e.g. Python. However on Leap 15.1 this standard procedure crashes with many QT warnings and errors, which are beyond me. The procedure for the parallel debugging session simply is to invoke a small number of processes on the command line like so

mpiexec -n 2 xterm -geometry 80x20 -e ipdb

where each process runs its own debugger (for Python, ipdb) within a terminal (eg. xterm).
Now, on Leap 15.1, interacting with the debugger within each of the xterms forked will eventually produce stuff like

WARNING: QApplication was not created in the main() thread.


QObject: Cannot create children for a parent that is in a different thread.
(Parent is QApplication(0x7fdd40001e90), parent's thread is QThread(0x7fdd40006390), current thread is QThread(0x7fdd400262f0)

Primarily this happens, if one tries to step or run between breakpoints.

Just to be absolutely clear, the app “” is free of QT-code or graphics. I.e. the QT warnings/errors stem from the operating system.

Any help to fix this would be most appreciated.

Although the guidelines for posting in this Applications forum is generally lax enough to allow development questions instead of the more typical User problems,
In this case, IMO the issues are Developer hard core enough to belong in the Developer forums instead

Am not sure how to address your problem
But would suggest that you don’t build on a Qt based DE like KDE/Plasma and LXQt,
Recommend that you instead build in a Gtk DE like Gnome or XFCE.
Or, maybe even in a Windows Manager only and no Desktop like IceWM which is installed in every default openSUSE but you can choose from a multitude of others too like Openbox, Fluxbox FVM2, and many, many more.

This is an example of why my SOP and recommendation is to do practically all my Development in virtual machines where the environment can be defined and controlled and without being polluted by anything that might cause problems.


Thx. for the link, and yes, I know, that with this issue I’m stuck in the middle of nowhere.

Maybe I should have said, that before posting here, it’s been my 1st stop to log out of the KDE and use exactly the default IceWM of that installation on that machine, my idea (maybe) being similar to yours.

However to my big surprise, I got exactly the same QT warnings/errors in the IceWM - where I also thought that there should be no QT around(?)

Does this tell you anything?


PS.: Is there any way to cross-link a thread over to another subforum here at, or does one have to restart from scratch?