February 8, 2023

The GIL is a major obstacle to concurrency. For scientific computing tasks, this lack of concurrency is often a bigger issue than speed of executing Python code, since most of the processor cycles are spent in optimized CPU or GPU kernels. The GIL introduces a global bottleneck that can prevent other threads from making progress if they call any Python code. There are existing ways to enable parallelism in CPython today, but those techniques come with significant limitations (see Alternatives). — PEP 703 – Making the Global Interpreter Lock Optional in CPython