Major Description
While working with a SQL with many CASE WHEN and ScalarSubqueries I faced the following exception (in Spark 2.3.0):
Caused by: java.lang.NullPointerException at org.apache.spark.sql.execution.FileSourceScanExec.<init>(DataSourceScanExec.scala:167) at org.apache.spark.sql.execution.FileSourceScanExec.doCanonicalize(DataSourceScanExec.scala:502) at org.apache.spark.sql.execution.FileSourceScanExec.doCanonicalize(DataSourceScanExec.scala:158) at org.apache.spark.sql.catalyst.plans.QueryPlan.canonicalized$lzycompute(QueryPlan.scala:210) at org.apache.spark.sql.catalyst.plans.QueryPlan.canonicalized(QueryPlan.scala:209) at org.apache.spark.sql.catalyst.plans.QueryPlan$$anonfun$2.apply(QueryPlan.scala:224) at org.apache.spark.sql.catalyst.plans.QueryPlan$$anonfun$2.apply(QueryPlan.scala:224) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234) at scala.collection.immutable.List.foreach(List.scala:381) at scala.collection.TraversableLike$class.map(TraversableLike.scala:234) at scala.collection.immutable.List.map(List.scala:285) at org.apache.spark.sql.catalyst.plans.QueryPlan.doCanonicalize(QueryPlan.scala:224) at org.apache.spark.sql.catalyst.plans.QueryPlan.canonicalized$lzycompute(QueryPlan.scala:210) at org.apache.spark.sql.catalyst.plans.QueryPlan.canonicalized(QueryPlan.scala:209) at org.apache.spark.sql.catalyst.plans.QueryPlan$$anonfun$2.apply(QueryPlan.scala:224) at org.apache.spark.sql.catalyst.plans.QueryPlan$$anonfun$2.apply(QueryPlan.scala:224) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234) at scala.collection.immutable.List.foreach(List.scala:381) at scala.collection.TraversableLike$class.map(TraversableLike.scala:234) at scala.collection.immutable.List.map(List.scala:285) at org.apache.spark.sql.catalyst.plans.QueryPlan.doCanonicalize(QueryPlan.scala:224) at org.apache.spark.sql.catalyst.plans.QueryPlan.canonicalized$lzycompute(QueryPlan.scala:210) at org.apache.spark.sql.catalyst.plans.QueryPlan.canonicalized(QueryPlan.scala:209) at org.apache.spark.sql.catalyst.plans.QueryPlan$$anonfun$2.apply(QueryPlan.scala:224) at org.apache.spark.sql.catalyst.plans.QueryPlan$$anonfun$2.apply(QueryPlan.scala:224) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234) at scala.collection.immutable.List.foreach(List.scala:381) at scala.collection.TraversableLike$class.map(TraversableLike.scala:234) at scala.collection.immutable.List.map(List.scala:285) at org.apache.spark.sql.catalyst.plans.QueryPlan.doCanonicalize(QueryPlan.scala:224) at org.apache.spark.sql.catalyst.plans.QueryPlan.canonicalized$lzycompute(QueryPlan.scala:210) at org.apache.spark.sql.catalyst.plans.QueryPlan.canonicalized(QueryPlan.scala:209) at org.apache.spark.sql.catalyst.plans.QueryPlan.sameResult(QueryPlan.scala:257) at org.apache.spark.sql.execution.ScalarSubquery.semanticEquals(subquery.scala:58) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$Expr.equals(EquivalentExpressions.scala:36) at scala.collection.mutable.HashTable$class.elemEquals(HashTable.scala:358) at scala.collection.mutable.HashMap.elemEquals(HashMap.scala:40) at scala.collection.mutable.HashTable$class.scala$collection$mutable$HashTable$$findEntry0(HashTable.scala:136) at scala.collection.mutable.HashTable$class.findEntry(HashTable.scala:132) at scala.collection.mutable.HashMap.findEntry(HashMap.scala:40) at scala.collection.mutable.HashMap.get(HashMap.scala:70) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions.addExpr(EquivalentExpressions.scala:54) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions.addExprTree(EquivalentExpressions.scala:95) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at scala.collection.immutable.List.foreach(List.scala:381) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions.addExprTree(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at scala.collection.immutable.List.foreach(List.scala:381) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions.addExprTree(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at scala.collection.immutable.List.foreach(List.scala:381) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions.addExprTree(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at scala.collection.immutable.List.foreach(List.scala:381) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions.addExprTree(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at scala.collection.immutable.List.foreach(List.scala:381) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions.addExprTree(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions$$anonfun$addExprTree$1.apply(EquivalentExpressions.scala:96) at scala.collection.immutable.List.foreach(List.scala:381) at org.apache.spark.sql.catalyst.expressions.EquivalentExpressions.addExprTree(EquivalentExpressions.scala:96) at org.apache.spark.sql.catalyst.expressions.codegen.CodegenContext$$anonfun$subexpressionElimination$1.apply(CodeGenerator.scala:1168) at org.apache.spark.sql.catalyst.expressions.codegen.CodegenContext$$anonfun$subexpressionElimination$1.apply(CodeGenerator.scala:1168) at scala.collection.immutable.List.foreach(List.scala:381) at org.apache.spark.sql.catalyst.expressions.codegen.CodegenContext.subexpressionElimination(CodeGenerator.scala:1168) at org.apache.spark.sql.catalyst.expressions.codegen.CodegenContext.generateExpressions(CodeGenerator.scala:1218) at org.apache.spark.sql.catalyst.expressions.codegen.GenerateUnsafeProjection$.createCode(GenerateUnsafeProjection.scala:310) at org.apache.spark.sql.catalyst.expressions.codegen.GenerateUnsafeProjection$.create(GenerateUnsafeProjection.scala:373) at org.apache.spark.sql.catalyst.expressions.codegen.GenerateUnsafeProjection$.generate(GenerateUnsafeProjection.scala:362) at org.apache.spark.sql.catalyst.expressions.UnsafeProjection$.create(Projection.scala:161) at org.apache.spark.sql.execution.ProjectExec$$anonfun$9.apply(basicPhysicalOperators.scala:71) at org.apache.spark.sql.execution.ProjectExec$$anonfun$9.apply(basicPhysicalOperators.scala:70) at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsWithIndexInternal$1$$anonfun$apply$24.apply(RDD.scala:818) at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsWithIndexInternal$1$$anonfun$apply$24.apply(RDD.scala:818) at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38) at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:324) at org.apache.spark.rdd.RDD.iterator(RDD.scala:288) at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38) at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:324) at org.apache.spark.rdd.RDD.iterator(RDD.scala:288) at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38) at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:324) at org.apache.spark.rdd.RDD.iterator(RDD.scala:288) at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38) at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:324) at org.apache.spark.rdd.RDD.iterator(RDD.scala:288) at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87) at org.apache.spark.scheduler.Task.run(Task.scala:109) at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:345) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748)
I've got the query and the parquet files that lead to the NPE, but cannot disclose it due to NDA. I've been trying to replicate it with different queries, but failed, and after over 3 days of exploring subexpression elimination I gave up.
The NPE technically is due to @transient relation: HadoopFsRelation that is not re-created on executors, but don't know why this @transient is required in the first place and more importantly how to write a test to reproduce it.
FYI Disabling subexpression elimination with spark.sql.subexpressionElimination.enabled Spark internal configuration property helps.
