Crashes after first successful start

[gustavz]

I can run this script exactly once and it works (more or less,somehow it does not print the fps)
But after ending it and restarting it does not work and keeps trying to build workers or whatever.
The only way to get it working again is to reboot.

Seems that the implementation of the multiprocessing/threading causes big problems.

Has anybody experienced the same? Or even better: Has found a solution?