Github user kayousterhout commented on a diff in the pull request:
https://github.com/apache/spark/pull/6352#discussion_r31165947
--- Diff:
core/src/test/scala/org/apache/spark/scheduler/DAGSchedulerSuite.scala ---
@@ -342,6 +342,29 @@ class DAGSchedulerSuite
assert(locs === Seq(Seq("hostA", "hostB"), Seq("hostB", "hostC"),
Seq("hostC", "hostD")))
}
+ /**
+ * +---+ shuffle +---+ +---+ +---+
+ * | A |<--------| B |<---| C |<---| D |
+ * +---+ +---+ +---+ +---+
+ * Here, D has one-to-one dependencies on C. C is derived from A by
performing a shuffle
+ * and then a map. If we're trying to determine which ancestor stages
need to be computed in
+ * order to compute D, we need to figure out whether the shuffle A -> B
should be performed.
+ * If the RDD C, which has only one ancestor via a narrow dependency, is
cached, then we won't
+ * need to compute A, even if it has some unavailable output partitions.
The same goes for B:
+ * if B is 100% cached, then we can avoid the shuffle on A.
+ */
+ test("SPARK-7826: getMissingParentStages should consider all ancestor
RDDs' cache statuses") {
--- End diff --
Can you remove "SPARK-7826" from the name of this test, since the test
isn't checking for the bug described by SPARK-7826? It's great to add this
test in the PR -- but having the JIRA name in the test name is something we
usually only do when the test is for the issue described by that JIRA.
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