Question

我的代码如下所示

 object ErrorTest {
case class APIResults(status:String, col_1:Long, col_2:Double, ...)

def funcA(rows:ArrayBuffer[Row])(implicit defaultFormats:DefaultFormats):ArrayBuffer[APIResults] = {
  //call some API ang get results and return APIResults
  ...
}

// MARK: load properties
val props = loadProperties()
private def loadProperties(): Properties =  {
  val configFile = new File("config.properties")
  val reader = new FileReader(configFile)
  val props = new Properties()
  props.load(reader)
  props
}

def main(args: Array[String]): Unit = {
  val prop_a = props.getProperty("prop_a")

  val session = Context.initialSparkSession();
  import session.implicits._

  val initialSet = ArrayBuffer.empty[Row]
  val addToSet = (s: ArrayBuffer[Row], v: Row) => (s += v)
  val mergePartitionSets = (p1: ArrayBuffer[Row], p2: ArrayBuffer[Row]) => (p1 ++= p2)

  val sql1 =
    s"""
       select * from tbl_a where ...
     """

  session.sql(sql1)
    .rdd.map{row => {implicit val formats = DefaultFormats; (row.getLong(6), row)}}
    .aggregateByKey(initialSet)(addToSet,mergePartitionSets)
    .repartition(40)
    .map{case (rowNumber,rows) => {implicit val formats = DefaultFormats; funcA(rows)}}
    .flatMap(x => x)
    .toDF()
    .write.mode(SaveMode.Overwrite).saveAsTable("tbl_b")
  }
}

当我通过spark-submit运行它时，它会抛出错误引起：java.lang.NoClassDefFoundError：无法初始化类staging_jobs.ErrorTest $ 。但是，如果我将val props = loadProperties()移动到main方法的第一行，那么就不会再出现错误了。谁能给我一个关于这种现象的解释？非常感谢！

Caused by: java.lang.NoClassDefFoundError: Could not initialize class staging_jobs.ErrorTest$
  at staging_jobs.ErrorTest$$anonfun$main$1.apply(ErrorTest.scala:208)
  at staging_jobs.ErrorTest$$anonfun$main$1.apply(ErrorTest.scala:208)
  at scala.collection.Iterator$$anon$11.next(Iterator.scala:409)
  at scala.collection.Iterator$$anon$12.nextCur(Iterator.scala:434)
  at scala.collection.Iterator$$anon$12.hasNext(Iterator.scala:440)
  at scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:408)
  at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.processNext(Unknown Source)
  at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
  at org.apache.spark.sql.execution.WholeStageCodegenExec$$anonfun$8$$anon$1.hasNext(WholeStageCodegenExec.scala:377)
  at org.apache.spark.sql.execution.datasources.FileFormatWriter$SingleDirectoryWriteTask.execute(FileFormatWriter.scala:243)
  at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$org$apache$spark$sql$execution$datasources$FileFormatWriter$$executeTask$3.apply(FileFormatWriter.scala:190)
  at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$org$apache$spark$sql$execution$datasources$FileFormatWriter$$executeTask$3.apply(FileFormatWriter.scala:188)
  at org.apache.spark.util.Utils$.tryWithSafeFinallyAndFailureCallbacks(Utils.scala:1341)
  at org.apache.spark.sql.execution.datasources.FileFormatWriter$.org$apache$spark$sql$execution$datasources$FileFormatWriter$$executeTask(FileFormatWriter.scala:193)
  ... 8 more

Answer 1

我遇到了和你一样的问题。我在convert方法之外定义了一个方法main。当我在dataframe.rdd.map{x => convert(x)}中与main一起使用时，发生了NoClassDefFoundError:Could not initialize class Test$。

但是当我在convertor方法中使用函数对象convert（与main方法相同的代码时），没有发生错误。

我使用了火花2.1.0，scala 2.11，它看起来像火花中的一个bug？

Answer 2

我想问题是val props = loadProperties()定义了外部类（main）的成员。然后，这个成员将被序列化（或运行）在执行程序上，这些执行程序没有带驱动程序的保存环境。

java.lang.NoClassDefFoundError：在scala代码中通过spark-submit启动spark作业时无法初始化类

2 个答案: