From Benjamin Reese on SLACK:

@slacrherbst
I managed to get this error, which core dumps the entire python program
Fatal Python error: PyThreadState_Get: the function must be called with the GIL held, but the GIL is released (the current Python thread state is NULL)
I think the problem is some things I'm doing with streams and not locking the frame, but I'm not sure the best way to do it.
My stream processing looks something like this
rawDataStream >> filterA >> receiverA
rawDataStream >> filterB >> receiverB
rawDataStream >> filterC >> receiverC
I think the issue is when a frame reaches receiverA, but filterB and filterC are not done with it.
But I could be way wrong about that.
The filters are custom python that filter based on the frame contents (not the channel number).