Python (and many interpreted languages) have something called GIL, Global interpreter lock. Because of this global lock, in multi threaded scenarios, only one thread can run at any given time, thus reducing it's usability. Threading usually used for parallelism but with GIL it'll only do concurrency. Many want gil to be removed from python yet no one has done it in a way with no performance loss (Gil provides better single threaded performance). David Beazley is removing 'GIL' using python3 and CNC. It's the worst joke I've ever seen in my entire python career.