What is the function of GIL and why is it needed in Python?

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

GIL is necessary to avoid complex race conditions and to ensure safe operation with Python objects without needing to use complex locks at each object level. However, due to GIL, multithreading in Python does not provide performance gains for CPU-bound tasks, as threads cannot run in parallel on multiple cores.

Example: multithreaded code performing computations will not be faster because of GIL, but for I/O-bound tasks (such as network requests, file reading), multithreading is useful because threads can switch during I/O wait times.