Accessing HBase tables through Spark

Question

I am using this code-example http://www.vidyasource.com/blog/Programming/Scala/Java/Data/Hadoop/Analytics/2014/01/25/lighting-a-spark-with-hbase to read a hbase table using Spark with the only change of adding the hbase.zookeeper.quorum through code as it is not picking it from the hbase-site.xml.

Spark 1.5.3 HBase 0.98.0

I am facing this error -

java.lang.IllegalAccessError: com/google/protobuf/HBaseZeroCopyByteString
at org.apache.hadoop.hbase.protobuf.RequestConverter.buildRegionSpecifier(RequestConverter.java:921)
at org.apache.hadoop.hbase.protobuf.RequestConverter.buildGetRowOrBeforeRequest(RequestConverter.java:132)
at org.apache.hadoop.hbase.protobuf.ProtobufUtil.getRowOrBefore(ProtobufUtil.java:1520)
at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateRegionInMeta(ConnectionManager.java:1294)
at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateRegion(ConnectionManager.java:1128)
at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateRegion(ConnectionManager.java:1111)
at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateRegion(ConnectionManager.java:1070)
at org.apache.hadoop.hbase.client.HTable.finishSetup(HTable.java:347)
at org.apache.hadoop.hbase.client.HTable.<init>(HTable.java:201)
at org.apache.hadoop.hbase.client.HTable.<init>(HTable.java:159)
at test.MyHBase.getTable(MyHBase.scala:33)
at test.MyHBase.<init>(MyHBase.scala:11)
at $line43.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw.fetch(<console>:30)
at $line44.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$anonfun$1.apply(<console>:49)
at $line44.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$anonfun$1.apply(<console>:49)
at scala.collection.Iterator$$anon$11.next(Iterator.scala:370)
at scala.collection.Iterator$class.foreach(Iterator.scala:742)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1194)
at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:59)
at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:104)
at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:48)
at scala.collection.TraversableOnce$class.to(TraversableOnce.scala:308)
at scala.collection.AbstractIterator.to(Iterator.scala:1194)
at scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:300)
at scala.collection.AbstractIterator.toBuffer(Iterator.scala:1194)
at scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:287)
at scala.collection.AbstractIterator.toArray(Iterator.scala:1194)
at org.apache.spark.rdd.RDD$$anonfun$collect$1$$anonfun$12.apply(RDD.scala:905)
at org.apache.spark.rdd.RDD$$anonfun$collect$1$$anonfun$12.apply(RDD.scala:905)
at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1848)
at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1848)
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:66)
at org.apache.spark.scheduler.Task.run(Task.scala:88)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:214)
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)

Answer 1

This is an HBase issue tracked and fixed in HBASE-10304 . The problem is that the HBaseZeroCopyByteString class is declared to be in the Protobuf library, but it's in a different jar file. In the end a different classloader loads it and cannot find the superclass declaration. It is fixed in HBase 0.99.

I think a workaround may be to make sure you include with the jars you submit to Spark the jars that contain com.google.protobuf.LiteralByteString and com.google.protobuf.HBaseZeroCopyByteString .

In the end you should really upgrade. Can you imagine the list of bugs that have been fixed since 0.98? Do you plan to hit them all and work around them one by one?