Github user pwendell commented on a diff in the pull request: https://github.com/apache/spark/pull/1039#discussion_r14642915 --- Diff: core/src/main/scala/org/apache/spark/rdd/RDD.scala --- @@ -1235,11 +1235,43 @@ abstract class RDD[T: ClassTag]( /** A description of this RDD and its recursive dependencies for debugging. */ def toDebugString: String = { - def debugString(rdd: RDD[_], prefix: String = ""): Seq[String] = { - Seq(prefix + rdd + " (" + rdd.partitions.size + " partitions)") ++ - rdd.dependencies.flatMap(d => debugString(d.rdd, prefix + " ")) + // Apply a different rule to the last child + def debugChildren(rdd: RDD[_], prefix: String): Seq[String] = { + val len = rdd.dependencies.length + len match { + case 0 => Seq.empty + case 1 => + val d = rdd.dependencies.head + debugString(d.rdd, prefix, d.isInstanceOf[ShuffleDependency[_,_]], true) + case _ => + val frontDeps = rdd.dependencies.take(len - 1) + val endDep = rdd.dependencies.takeRight(1).head + (frontDeps.flatMap(d => debugString(d.rdd, prefix, d.isInstanceOf[ShuffleDependency[_,_]])) + ++ debugString(endDep.rdd, prefix, endDep.isInstanceOf[ShuffleDependency[_,_]], true)) + } + } + // The first RDD in the dependency stack has no parents, so no need for a +- + def firstDebugString(rdd: RDD[_]): Seq[String] = { --- End diff -- It might be good to make all these inner functions private to avoid having to deal with binary checker changes in the future.
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