[AcidWeb]

Well I made some additional tests and results are ever more puzzling.

If I extract my Python3 version of your code and run standalone - It run correctly.
If I extract my Python3 version of your code and run standalone as QRunnable thread (Like my program) - It run correctly.
If I run it as QRunnable thread from my program - MemoryError.
If I run it from my program main worker QThread - MemoryError.

As we can see apparently that is not directly connected to your code. Either way debugging that will be pain :-)

Thank you.