What is GIL?

GIL (Global Interpreter Lock) is a mechanism in CPython that ensures only one thread executes Python bytecode at a time.

It is implemented to simplify memory management and prevent thread safety issues in the interpreter. Due to the GIL, multithreaded Python programs cannot efficiently utilize multiple CPU cores for CPU-bound tasks.

To bypass the GIL, the following are used:

• Multiprocessing (the multiprocessing module)
• C extensions that release the GIL during heavy computations
• Alternative Python implementations without GIL (e.g., Jython, IronPython)

Example of using multiprocessing:

from multiprocessing import Pool

def f(x):
    return x*x

with Pool(4) as p:
    print(p.map(f, [1, 2, 3, 4]))