OS//concurrency//mutex//GIL

The GIL (Global Interpreter Lock) is Python's mutex that ensures only one thread executes bytecode at a time. It simplifies memory management, because reference counting is thread-safe without fine-grained locks, and it prevents true core parallelism for CPU-bound tasks.

The GIL (Global Interpreter Lock) is Python's mutex that ensures only one thread executes bytecode at a time. It simplifies memory management, because reference counting is thread-safe without fine-grained locks, and it prevents true core parallelism for CPU-bound tasks.

The workarounds are multiprocessing, C extensions that release the GIL, and async I/O through the event loop. Python 3.13 and later experiment with a free-threaded build (a no-GIL mode).