PyCharm: Faster Python: Unlocking the Python Global Interpreter Lock

Python's Global Interpreter Lock (GIL) is a mutex that allows only one thread to access the Python interpreter at a time. This prevents true multithreaded processes in Python by design. The GIL was implemented to prevent race conditions and simplify garbage collection through reference counting. In Python's early days, single-core processors and less demand for multithreading made the GIL beneficial for code simplicity. However, modern multi-core processors highlight the GIL's limitations for parallel execution. To achieve concurrency, Python developers often use the multiprocessing library, which bypasses the GIL by creating separate processes. Multiprocessing requires different programming patterns, such as using Queues and Locks for inter-process communication. Removing the GIL has been a long-standing goal in the Python community, with recent efforts leading to optional GIL removal in Python 3.13. Removing the GIL introduces complexities, particularly concerning thread-safe reference counting. Biased reference counting is a proposed solution to maintain efficiency while ensuring thread safety without the GIL.