deadlock.py

from concurrent.futures import ProcessPoolExecutor
from multiprocessing import Lock


class A:

    def __init__(self):
        """Uncomment the line blow to stuck in deadlock.
        """
        #self.lock = Lock()  # deadlock

    def __call__(self):
        with ProcessPoolExecutor(4) as pool:
            future = pool.submit(self.job)#lambda x: print(x), 'hello')
            pool.shutdown()

    def job(self):
        print('hello, world')

if __name__ == '__main__':
    A()()