Question

我有一个Java类，它有几个String字段和一个HashMap字段。我正在使用默认的Kryo序列化序列化此类的对象并将它们存储在HBase中。

在内存中读取它们后，Spark中RDD的flatMap函数中的反序列化会产生以下错误。虽然相同的代码段可以工作，但它不涉及Spark。

    16/06/22 11:13:05 WARN TaskSetManager: Lost task 20.0 in stage 3.0 (TID 85, localhost): com.esotericsoftware.kryo.KryoException: Unable to find class: Dadaisme
    at com.esotericsoftware.kryo.util.DefaultClassResolver.readName(DefaultClassResolver.java:138)
    at com.esotericsoftware.kryo.util.DefaultClassResolver.readClass(DefaultClassResolver.java:115)
    at com.esotericsoftware.kryo.Kryo.readClass(Kryo.java:610)
    at com.esotericsoftware.kryo.Kryo.readClassAndObject(Kryo.java:721)
    at com.esotericsoftware.kryo.serializers.MapSerializer.read(MapSerializer.java:126)
    at com.esotericsoftware.kryo.serializers.MapSerializer.read(MapSerializer.java:17)
    at com.esotericsoftware.kryo.Kryo.readClassAndObject(Kryo.java:729)
    at prSpark.EmPageRank$1.call(EmPageRank.java:227)
    at prSpark.EmPageRank$1.call(EmPageRank.java:1)
    at org.apache.spark.api.java.JavaRDDLike$$anonfun$fn$3$1.apply(JavaRDDLike.scala:149)
    at org.apache.spark.api.java.JavaRDDLike$$anonfun$fn$3$1.apply(JavaRDDLike.scala:149)
    at scala.collection.Iterator$$anon$13.hasNext(Iterator.scala:371)
    at org.apache.spark.util.Utils$.getIteratorSize(Utils.scala:1595)
    at org.apache.spark.rdd.RDD$$anonfun$count$1.apply(RDD.scala:1157)
    at org.apache.spark.rdd.RDD$$anonfun$count$1.apply(RDD.scala:1157)
    at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1858)
    at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1858)
    at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:66)
    at org.apache.spark.scheduler.Task.run(Task.scala:89)
    at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:214)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: Dadaisme
    at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:340)
    at com.esotericsoftware.kryo.util.DefaultClassResolver.readName(DefaultClassResolver.java:136)
    ... 22 more

这里来自堆栈跟踪com.esotericsoftware.kryo.KryoException: Unable to find class: Dadaisme它说“Dadisme”类没有找到但是“Dadisme”不是我程序中的任何类，它是HashMap字段中的数据。

Answer 1

发生此异常是因为用于序列化和反序列化的Kyro库中的版本差异。 Spark默认使用Kryo的第2版，我使用Kryo的最新版本（即3.x）进行对象的序列化。所以序列化和反序列化版本应该匹配。

HashMap的Kryo反序列化因Spark而失败

1 个答案: