> Hummm, the test case from this bug is precisely the test case in PR 19009 so it should not hang.

Oh, actually I am wrong as this is a different issue I had in mind. PR 19009 should fix the case reported in https://bugs.python.org/issue38744 and this equivalent:

          from multiprocessing import Pool
            class A:
                def __init__(self):
                    self.pool = Pool(processes=1)
            def test():
                problem = A()
                problem.pool.map(float, tuple(range(10)))
            if __name__ == "__main__":
                test()

Notice that in this code there is no __del__ call.