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首页 > 解决方案 > 为什么 Some(null) 在 Spark 2.4 中抛出 NullPointerException（但在 2.2 中有效）？

scala - 为什么 Some(null) 在 Spark 2.4 中抛出 NullPointerException（但在 2.2 中有效）？

问题描述

此代码过去在 Spark 2.2 Scala 2.11.x 下有效，但在 Spark 2.4 中无效。

val df = Seq(
  (1, Some("a"), Some(1)),
  (2, Some(null), Some(2)),
  (3, Some("c"), Some(3)),
  (4, None, None)
).toDF("c1", "c2", "c3")

我在 Spark 2.4 中运行它，现在它给出了错误：

scala> spark.version
res0: String = 2.4.0

scala> :pa
// Entering paste mode (ctrl-D to finish)

val df = Seq(
  (1, Some("a"), Some(1)),
  (2, Some(null), Some(2)),
  (3, Some("c"), Some(3)),
  (4, None, None)
).toDF("c1", "c2", "c3")

// Exiting paste mode, now interpreting.

java.lang.RuntimeException: Error while encoding: java.lang.NullPointerException
assertnotnull(assertnotnull(input[0, scala.Tuple3, true]))._1 AS _1#6
staticinvoke(class org.apache.spark.unsafe.types.UTF8String, StringType, fromString, unwrapoption(ObjectType(class java.lang.String), assertnotnull(assertnotnull(input[0, scala.Tuple3, true]))._2), true, false) AS _2#7
unwrapoption(IntegerType, assertnotnull(assertnotnull(input[0, scala.Tuple3, true]))._3) AS _3#8
  at org.apache.spark.sql.catalyst.encoders.ExpressionEncoder.toRow(ExpressionEncoder.scala:293)
  at org.apache.spark.sql.SparkSession.$anonfun$createDataset$1(SparkSession.scala:472)
  at scala.collection.TraversableLike.$anonfun$map$1(TraversableLike.scala:233)
  at scala.collection.immutable.List.foreach(List.scala:388)
  at scala.collection.TraversableLike.map(TraversableLike.scala:233)
  at scala.collection.TraversableLike.map$(TraversableLike.scala:226)
  at scala.collection.immutable.List.map(List.scala:294)
  at org.apache.spark.sql.SparkSession.createDataset(SparkSession.scala:472)
  at org.apache.spark.sql.SQLContext.createDataset(SQLContext.scala:377)
  at org.apache.spark.sql.SQLImplicits.localSeqToDatasetHolder(SQLImplicits.scala:228)
  ... 57 elided
Caused by: java.lang.NullPointerException
  at org.apache.spark.sql.catalyst.expressions.codegen.UnsafeWriter.write(UnsafeWriter.java:109)
  at org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.apply(Unknown Source)
  at org.apache.spark.sql.catalyst.encoders.ExpressionEncoder.toRow(ExpressionEncoder.scala:289)
  ... 66 more

我很好奇发生了什么变化以及为什么要更换这条线：

(2, Some(null), Some(2)),

和：

(2, None, Some(2)),

解决了这个问题。

发生了什么变化，这对现有代码库意味着什么？

标签： scalaapache-spark

解决方案

被认为是一个错误并报告为SPARK-26984。

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