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https://issues.apache.org/jira/browse/SPARK-18737?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15781418#comment-15781418
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Josh Bacon commented on SPARK-18737:
------------------------------------

My team is experiencing the exact same issue as described by OP for our 
streaming jobs using KinesisUtils library. Code worked in 1.6 previously but 
now experiences KyroExceptions in 2.0 (Unregistered Class Id) no matter if 
JavaSerialization is enabled instead or if requireRegister is set to false. 
Errors are experienced in non-deterministic manor as well. We see no 
work-around currently for our jobs in Spark 2.0.1.

> Serialization setting "spark.serializer" ignored in Spark 2.x
> -------------------------------------------------------------
>
>                 Key: SPARK-18737
>                 URL: https://issues.apache.org/jira/browse/SPARK-18737
>             Project: Spark
>          Issue Type: Bug
>    Affects Versions: 2.0.0, 2.0.1
>            Reporter: Dr. Michael Menzel
>
> The following exception occurs although the JavaSerializer has been activated:
> 16/11/22 10:49:24 INFO TaskSetManager: Starting task 0.0 in stage 9.0 (TID 
> 77, ip-10-121-14-147.eu-central-1.compute.internal, partition 1, RACK_LOCAL, 
> 5621 bytes)
> 16/11/22 10:49:24 INFO YarnSchedulerBackend$YarnDriverEndpoint: Launching 
> task 77 on executor id: 2 hostname: 
> ip-10-121-14-147.eu-central-1.compute.internal.
> 16/11/22 10:49:24 INFO BlockManagerInfo: Added broadcast_11_piece0 in memory 
> on ip-10-121-14-147.eu-central-1.compute.internal:45059 (size: 879.0 B, free: 
> 410.4 MB)
> 16/11/22 10:49:24 WARN TaskSetManager: Lost task 0.0 in stage 9.0 (TID 77, 
> ip-10-121-14-147.eu-central-1.compute.internal): 
> com.esotericsoftware.kryo.KryoException: Encountered unregistered class ID: 
> 13994
>         at 
> com.esotericsoftware.kryo.util.DefaultClassResolver.readClass(DefaultClassResolver.java:137)
>         at com.esotericsoftware.kryo.Kryo.readClass(Kryo.java:670)
>         at com.esotericsoftware.kryo.Kryo.readClassAndObject(Kryo.java:781)
>         at 
> org.apache.spark.serializer.KryoDeserializationStream.readObject(KryoSerializer.scala:229)
>         at 
> org.apache.spark.serializer.DeserializationStream$$anon$1.getNext(Serializer.scala:169)
>         at org.apache.spark.util.NextIterator.hasNext(NextIterator.scala:73)
>         at scala.collection.Iterator$class.foreach(Iterator.scala:893)
>         at org.apache.spark.util.NextIterator.foreach(NextIterator.scala:21)
>         at 
> scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:59)
>         at 
> scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:104)
>         at 
> scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:48)
>         at 
> scala.collection.TraversableOnce$class.to(TraversableOnce.scala:310)
>         at org.apache.spark.util.NextIterator.to(NextIterator.scala:21)
>         at 
> scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:302)
>         at org.apache.spark.util.NextIterator.toBuffer(NextIterator.scala:21)
>         at 
> scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:289)
>         at org.apache.spark.util.NextIterator.toArray(NextIterator.scala:21)
>         at 
> org.apache.spark.rdd.RDD$$anonfun$toLocalIterator$1$$anonfun$org$apache$spark$rdd$RDD$$anonfun$$collectPartition$1$1.apply(RDD.scala:927)
>         at 
> org.apache.spark.rdd.RDD$$anonfun$toLocalIterator$1$$anonfun$org$apache$spark$rdd$RDD$$anonfun$$collectPartition$1$1.apply(RDD.scala:927)
>         at 
> org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1916)
>         at 
> org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1916)
>         at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:70)
>         at org.apache.spark.scheduler.Task.run(Task.scala:86)
>         at 
> org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:274)
>         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)
> The code runs perfectly with Spark 1.6.0. Since we moved to 2.0.0 and now 
> 2.0.1, we see the Kyro deserialization exception and over time the Spark 
> streaming job stops processing since too many tasks failed.
> Our action was to use conf.set("spark.serializer", 
> "org.apache.spark.serializer.JavaSerializer") and to disable Kryo class 
> registration with conf.set("spark.kryo.registrationRequired", false). We hope 
> to identify the root cause of the exception. 
> However, setting the serializer to JavaSerializer is oviously ignored by the 
> Spark-internals. Despite the setting we still see the exception printed in 
> the log and tasks fail. The occurence seems to be non-deterministic, but to 
> become more frequent over time.
> Several questions we could not answer during our troubleshooting:
> 1. How can the debug log for Kryo be enabled? -- We tried following the 
> minilog documentation, but no output can be found.
> 2. Is the serializer setting effective for Spark internal serializations? How 
> can the JavaSerialize be forced on internal serializations for worker to 
> driver communication?



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