apache/spark — pull request #1364 by GregOwen (2014-07-10 23:14:13+00:00)
Title: [SPARK-2086] Improve output of toDebugString to make shuffle boundaries more clear

Changes RDD.toDebugString() to show hierarchy and shuffle transformations more clearly

New output:

```
(3) FlatMappedValuesRDD[325] at apply at Transformer.scala:22
| MappedValuesRDD[324] at apply at Transformer.scala:22
| CoGroupedRDD[323] at apply at Transformer.scala:22
+-(5) MappedRDD[320] at apply at Transformer.scala:22
| | MappedRDD[319] at apply at Transformer.scala:22
| | MappedValuesRDD[318] at apply at Transformer.scala:22
| | MapPartitionsRDD[317] at apply at Transformer.scala:22
| | ShuffledRDD[316] at apply at Transformer.scala:22
| +-(10) MappedRDD[315] at apply at Transformer.scala:22
| | ParallelCollectionRDD[314] at apply at Transformer.scala:22
+-(100) MappedRDD[322] at apply at Transformer.scala:22
| ParallelCollectionRDD[321] at apply at Transformer.scala:22
```