Crash if mapper or reducer does not yield anything

[a4tunado]

Some jobs do not produce any output for ex. uploading input data to external storage or something like this. Dumbo expected that each reducer or mapper yields some data otherwise it leads to crash.

[ediskandarov]

You can create empty generator like this

def reducer(data):
    for key, values in data:
        # do something

    return
    yield