[SPARK-20404] Regression with accumulator names when migrating from 1.6 to 2.x

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0.0, 2.0.1, 2.0.2, 2.1.0
• Fix Version/s: 2.1.2, 2.2.0
• Component/s: Spark Core

Environment

Spark: 2.1
Scala: 2.11
Spark master: local

• Flags: Patch
• Assignee: Sergey Zhemzhitsky
• Reporter: Sergey Zhemzhitsky
• Created: 20/Apr/17 07:29
• Updated: 25/Apr/17 08:20
• Resolved: 25/Apr/17 08:19

Description

Creating accumulator with explicitly specified name equal to null, like the following

sparkContext.accumulator(0, null)

throws exception at runtime

ERROR | DAGScheduler | dag-scheduler-event-loop | Failed to update accumulators for task 0
java.lang.NullPointerException
	at org.apache.spark.util.AccumulatorV2$$anonfun$1.apply(AccumulatorV2.scala:106)
	at org.apache.spark.util.AccumulatorV2$$anonfun$1.apply(AccumulatorV2.scala:106)
	at scala.Option.exists(Option.scala:240)
	at org.apache.spark.util.AccumulatorV2.toInfo(AccumulatorV2.scala:106)
	at org.apache.spark.scheduler.DAGScheduler$$anonfun$updateAccumulators$1.apply(DAGScheduler.scala:1091)
	at org.apache.spark.scheduler.DAGScheduler$$anonfun$updateAccumulators$1.apply(DAGScheduler.scala:1080)
	at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
	at org.apache.spark.scheduler.DAGScheduler.updateAccumulators(DAGScheduler.scala:1080)
	at org.apache.spark.scheduler.DAGScheduler.handleTaskCompletion(DAGScheduler.scala:1183)
	at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:1647)
	at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1605)
	at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1594)
	at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:48)

The issue is in wrapping name into Some instead of Option when creating accumulators.

Patch is available.

Issue Links

• links to: [Github] Pull Request #17740 (szhem)