LocalCheckpointRDD[T] is a CheckpointRDD.
LocalCheckpointRDD takes the following to be created:
LocalCheckpointRDD is created when:
LocalRDDCheckpointDatais requested to doCheckpoint
getPartitions is part of the RDD abstraction.
getPartitions creates a
CheckpointRDDPartition for every input partition (index).
compute( partition: Partition, context: TaskContext): Iterator[T]
compute is part of the RDD abstraction.
compute merely throws an
SparkException (that explains the reason):
Checkpoint block [RDDBlockId] not found! Either the executor that originally checkpointed this partition is no longer alive, or the original RDD is unpersisted. If this problem persists, you may consider using `rdd.checkpoint()` instead, which is slower than local checkpointing but more fault-tolerant."