import time
from concurrent.futures import ProcessPoolExecutor


class ExceptionWithoutState(Exception):
    pass


class ExceptionWithState(Exception):
    def __init__(self, state: str):
        super().__init__()
        self.state = state


def main():
    """
    Minimal reproduction example.

    This routine will display the following output:

    ```
    <class '__main__.ExceptionWithoutState'>

    <class 'concurrent.futures.process.BrokenProcessPool'>
    A process in the process pool was terminated abruptly while the future was
    running or pending.
    ```

    In the first case the stateless exception is properly pickled and
    propagated back to the parent process. In the second case, somehow, raising
    the exception with state cause a `BrokenProcessPool` exception instead.

    I read there was some fixes that were push regarding the multithreading
    module and pickling... Maybe its related?
    """
    with ProcessPoolExecutor() as executor:
        future = executor.submit(work_1)

        while not future.done():
            time.sleep(0.0)

        exception = future.exception()

        print(type(exception))
        print(exception)

        future = executor.submit(work_2)

        while not future.done():
            time.sleep(0.0)

        exception = future.exception()

        print(type(exception))
        print(exception)


def work_1():
    raise ExceptionWithoutState()


def work_2():
    raise ExceptionWithState(state="Fails when has state.")


if __name__ == "__main__":
    main()