What is "free-threaded mode" and what impact does it have on Python applications?

Free-threaded mode in Python disables the Global Interpreter Lock (GIL), allowing true parallel execution of threads on multiple CPU cores. This enhances performance for CPU-bound multithreaded programs but requires thread-safe code and introduces some overhead.

Free-threaded mode removes the GIL limitation, enabling threads to run in parallel across cores, improving CPU-bound task performance. However, it demands careful handling of thread safety and may increase overhead in single-threaded code.

Code

import threading

def task():
    # CPU-intensive task
    pass

threads = [threading.Thread(target=task) for _ in range(4)]
for t in threads:
    t.start()
for t in threads:
    t.join()