In this blog post, the author dives into the details of CPython’s Global Interpreter Lock (GIL) and examines how it has evolved from Python 3.9 to Python 3.13. The GIL is a single global lock that protects CPython’s internal data structures from concurrent access. While the GIL simplifies implementation and ensures correctness, it also limits the ability to execute Python bytecode in parallel, posing a performance bottleneck for certain applications. The author explores the “guarantees” provided by the GIL, particularly in terms of atomicity, and discusses potential pitfalls of relying on these guarantees when developing concurrent Python code. The post includes examples and demonstrations of GIL behavior in different versions of Python, PyPy, and GraalPy. The author concludes by suggesting the addition of a compile-time option in CPython to simulate a no-GIL implementation for testing purposes.
https://stefan-marr.de/2023/11/python-global-interpreter-lock/