from multiprocessing.pool import Pool
#from multiprocessing.pool import ThreadPool as Pool

def double(x):
    return 2 * x

def get_numbers():
    raise Exception("oops")
    yield 1
    yield 2

def get_numbers_differently():
    yield 1
    raise Exception("oops")
    yield 2


if __name__ == '__main__':
    # Used to result in no exception, disappointingly
    try:
        for result in Pool(processes=2).imap(double, get_numbers()):
            print("RESULT:", result)
        print("1st try:  imap did not trigger exception")
    except Exception as e:
        print("1st try:  imap triggered exception: %r" % (e,))

    # Repeated use of imap also used to have problems
    try:
        for result in Pool(processes=2).imap(double, get_numbers()):
            print("RESULT:", result)
        print("2nd try:  imap did not trigger exception")
    except Exception as e:
        print("2nd try:  imap triggered exception: %r" % (e,))

    # Results in exception
    try:
        print("RESULT:", Pool(processes=2).map(double, get_numbers()))
    except Exception as e:
        print("map triggered exception: %r" % (e,))

    # Results in exception
    try:
        for result in Pool(processes=2).imap(double, get_numbers_differently()):
            print("RESULT:", result)
    except Exception as e:
        print("imap triggered exception: %r" % (e,))
        #raise e

    # Also results in exception
    try:
        print("RESULT:", Pool(processes=2).map(double, get_numbers_differently()))
    except Exception as e:
        print("map triggered exception: %r" % (e,))

    # Used to result in no exception, disappointingly
    try:
        for result in Pool(processes=2).imap_unordered(double, get_numbers()):
            print("RESULT:", result)
        print("1st try:  imap_unordered did not trigger exception")
    except Exception as e:
        print("1st try:  imap_unordered triggered exception: %r" % (e,))

    # Repeated use of imap_unordered also used to have problems
    try:
        for result in Pool(processes=2).imap_unordered(double, get_numbers()):
            print("RESULT:", result)
        print("2nd try:  imap_unordered did not trigger exception")
    except Exception as e:
        print("2nd try:  imap_unordered triggered exception: %r" % (e,))

    # Results in exception
    try:
        for result in Pool(processes=2).imap_unordered(double, get_numbers_differently()):
            print("RESULT:", result)
    except Exception as e:
        print("imap_unordered triggered exception: %r" % (e,))
        #raise e