Make sure to have git, python and pip in your environment path or activate your python environment. from dmx import DMX import time dmx = DMX(num_of_channels=4) dmx.set_data(1, 0) dmx.set_data(2, 0) ...

The easiest way to see the carnage in action is to run it under gdb and break on PyInit__multiarray_umath. You'll see it gets called twice, the second time reentrantly (with a 276-frame backtrace ...