How to register array class with Kyro in spark-defaults.conf

[Wang, Ningjun (LNG-NPV)]

I register my class with Kyro in spark-defaults.conf as follow

spark.serializer                                   
org.apache.spark.serializer.KryoSerializer
spark.kryo.registrationRequired                     true
spark.kryo.classesToRegister  ltn.analytics.es.EsDoc

But I got the following exception

java.lang.IllegalArgumentException: Class is not registered: 
ltn.analytics.es.EsDoc[]
Note: To register this class use: kryo.register(ltn.analytics.es.EsDoc[].class);
            at com.esotericsoftware.kryo.Kryo.getRegistration(Kryo.java:442)
            at 
com.esotericsoftware.kryo.util.DefaultClassResolver.writeClass(DefaultClassResolver.java:79)
            at com.esotericsoftware.kryo.Kryo.writeClass(Kryo.java:472)
            at com.esotericsoftware.kryo.Kryo.writeClassAndObject(Kryo.java:565)
            at 
org.apache.spark.serializer.KryoSerializerInstance.serialize(KryoSerializer.scala:162)
            at 
org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:213)
            at 
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
            at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
            at java.lang.Thread.run(Thread.java:745)

The error message seems to suggest that I should also register the array class 
EsDoc[]. So I add it to spark-defaults.conf as follow

spark.kryo.classesToRegister  ltn.analytics.es.EsDoc,ltn.analytics.es.EsDoc[]

Then I got the following error

org.apache.spark.SparkException: Failed to register classes with Kryo
            at 
org.apache.spark.serializer.KryoSerializer.newKryo(KryoSerializer.scala:101)
            at 
org.apache.spark.serializer.KryoSerializerInstance.<init>(KryoSerializer.scala:153)
            at 
org.apache.spark.serializer.KryoSerializer.newInstance(KryoSerializer.scala:115)
            at 
org.apache.spark.broadcast.TorrentBroadcast$.blockifyObject(TorrentBroadcast.scala:200)
            at 
org.apache.spark.broadcast.TorrentBroadcast.writeBlocks(TorrentBroadcast.scala:101)
            at 
org.apache.spark.broadcast.TorrentBroadcast.<init>(TorrentBroadcast.scala:84)
            at 
org.apache.spark.broadcast.TorrentBroadcastFactory.newBroadcast(TorrentBroadcastFactory.scala:34)
            at 
org.apache.spark.broadcast.TorrentBroadcastFactory.newBroadcast(TorrentBroadcastFactory.scala:29)
            at 
org.apache.spark.broadcast.BroadcastManager.newBroadcast(BroadcastManager.scala:62)
            at org.apache.spark.SparkContext.broadcast(SparkContext.scala:1051)
            at ltn.analytics.index.Index.addDocuments(Index.scala:82)
Please advise.

Thanks.
Ningjun