What role does GIL play in the Python interpreter and why is it needed?

GIL (Global Interpreter Lock) is a mechanism in CPython that ensures only one thread executes Python bytecode at a time. This is done to simplify memory management and prevent issues with concurrent access to internal interpreter structures.

GIL is necessary to avoid complex race conditions and errors when working with Python objects, as many of them are not thread-safe. However, due to GIL, multithreaded Python programs cannot efficiently utilize multiple CPU cores for CPU-bound tasks, although for I/O-bound tasks, multithreading works fine.

Example: if you have several threads performing computations in Python, GIL will switch control between them but will not allow them to execute bytecode simultaneously, which limits parallelism.

To bypass GIL, developers often use multiprocessing or C extensions that release the GIL during heavy computations.