问题
I'd like to compute the difference (by key) of two DStreams with different windows. This could be accomplished with a join. However, I want to have an offset between the DStreams. One way to do this would be to drop N windows of one of the DStreams, but I don't know how to do that either.
来源：https://stackoverflow.com/questions/26445407/how-can-i-perform-an-operation-on-two-windowed-dstreams-with-an-offset