The GIL is dead: PyPy-STM

Take a big, non-multithreaded program, and run in on multiple cores!

PyPy, the Python implementation written in Python, experimentally supports Software Transactional Memory (STM). It runs without the Global Interpreter Lock (GIL).

The strength of STM is not only to remove the GIL, but to also enable a novel use of multithreading, inheritently safe, and more useful in the general case than other approaches like OpenMP. The main news from last year’s presentation is that there is now a way to get reports about the “STM conflicts”, which is essential to go past toy examples. With it, you can incrementally remove conflicts from large code bases until you see a benefit from PyPy-STM. The goal of the talk is to give several concrete examples of doing that.