参考：
Hadoop MapReduce中如何处理跨行Block和UnputSplit
https://stackoverflow.com/questions/17727468/hadoop-input-split-size-vs-block-size
https://stackoverflow.com/questions/30549261/split-size-vs-block-size-in-hadoop
参考：
https://stackoverflow.com/questions/17727468/hadoop-input-split-size-vs-block-size
https://stackoverflow.com/questions/30549261/split-size-vs-block-size-in-hadoop