Python - David Beazley's "Understanding The Python GIL"

20 Jan 2017 This talk explains a lot about Python's multithreading: http://www.dabeaz.com/python/UnderstandingGIL.pdf

In Python 2.7, it knows to switch to different thread whenever it starts waiting on IO. And, it will check if it needs to switch threads every 100 bytecode instructions.