[SPARK-16193] Address flaky ExternalAppendOnlyMapSuite spilling tests

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 2.0.0
• Component/s: Spark Core, Tests
• Target Version/s: 2.0.0
• Assignee: Sean R. Owen
• Reporter: Sean R. Owen
• Created: 24/Jun/16 20:49
• Updated: 28/Jun/16 20:46
• Resolved: 25/Jun/16 11:14

Description

We've seen tests fail, for different codecs and operations, like so, most recently from 2.0.0 RC1:

- spilling with compression *** FAILED ***
  java.lang.Exception: Test failed with compression using codec org.apache.spark.io.LZ4CompressionCodec:

assertion failed: expected groupByKey to spill, but did not
  at scala.Predef$.assert(Predef.scala:170)
  at org.apache.spark.TestUtils$.assertSpilled(TestUtils.scala:170)
  at org.apache.spark.util.collection.ExternalAppendOnlyMapSuite.org$apache$spark$util$collection$ExternalAppendOnlyMapSuite$$testSimpleSpilling(ExternalAppendOnlyMapSuite.scala:253)
  at org.apache.spark.util.collection.ExternalAppendOnlyMapSuite$$anonfun$10$$anonfun$apply$mcV$sp$8.apply(ExternalAppendOnlyMapSuite.scala:218)
  at org.apache.spark.util.collection.ExternalAppendOnlyMapSuite$$anonfun$10$$anonfun$apply$mcV$sp$8.apply(ExternalAppendOnlyMapSuite.scala:216)
  at scala.collection.immutable.Stream.foreach(Stream.scala:594)
  ...

My theory is that the listener doesn't receive notification of the spilled stages early enough to show up in the test. It should wait until the job is done before letting the test proceed to query the number of spilled stages.

Issue Links

• relates to: SPARK-11078 Ensure spilling tests are actually spilling
• links to: [Github] Pull Request #13896 (srowen)