Analogous to org.apache.spark.rdd.MapPartitionsRDD, but passes in an InputSplit to the given function rather than the index of the partition.
Configuration's constructor is not threadsafe (see SPARK-1097 and HADOOP-10456).
Configuration's constructor is not threadsafe (see SPARK-1097 and HADOOP-10456). Therefore, we synchronize on this lock before calling new JobConf() or new Configuration().
Update the input bytes read metric each time this number of records has been read
Add Hadoop configuration specific to a single partition and attempt.