After https://github.com/python/cpython/pull/18334, a "while condition: pass" in a thread will preclude releasing the GIL, hanging the program with CPU at 100%.

Trivial to reproduce:

"""
#!/usr/bin/env python3.10

import threading
import time

def worker():
    while cont:
        pass

def main():
    global cont
    cont = True
    t = threading.Thread(target=worker)
    t.start()
    time.sleep(1)
    cont = False
    t.join()

if __name__ == '__main__':
    main()
"""