How can I get KODI and a Python script to run at the same time?

Question

I have created a small program in Python 3 (3.7.3) to monitor the supply voltage of the uninterruptible power supply (UPS). If the voltage is switched off, the system should be shut down in a controlled manner.

• First I called KODI (18.7) and the Python script from 'autostart'

(*/etc/xdg/lxsession/LXDE-pi/autostart*) 

and realised that only KODI is running and the script is not.

• Then I called KODI from my script after running two monitoring loops. When KODI started, the script froze and continued exactly where it left off when KODI was stopped.

• I then started KODI from the menu (Menu --> Entertainment media --> KODI) and, strangely enough, both programs worked in parallel.