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https://issues.apache.org/jira/browse/HIVE-7799?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14107139#comment-14107139
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Venki Korukanti commented on HIVE-7799:
---------------------------------------
Whenever {{ResultIterator.hasNext()}} or {{ResultIterator.next()}} is called we
first serve records from RowContainer until all records in RowContainer are
consumed. If there are no more records in RowContainer then we clear
RowContainer and call {{processNextRecord}} or {{closeRecordProcessor}} in
{{ResultIterator.hasNext()}} to get the next output record(s). So we start
adding records only when RowContainer is empty (or cleared). I am trying to
understand how we got into the situation where we are trying to write after
reading has started. One scenario I can think of is if Spark has two threads
like in producer-consumer.
> TRANSFORM failed in transform_ppr1.q[Spark Branch]
> --------------------------------------------------
>
> Key: HIVE-7799
> URL: https://issues.apache.org/jira/browse/HIVE-7799
> Project: Hive
> Issue Type: Bug
> Components: Spark
> Reporter: Chengxiang Li
> Assignee: Chengxiang Li
> Labels: Spark-M1
> Attachments: HIVE-7799.1-spark.patch, HIVE-7799.2-spark.patch
>
>
> Here is the exception:
> {noformat}
> 2014-08-20 01:14:36,594 ERROR executor.Executor (Logging.scala:logError(96))
> - Exception in task 0.0 in stage 1.0 (TID 0)
> java.lang.NullPointerException
> at
> org.apache.hadoop.hive.ql.exec.spark.HiveKVResultCache.next(HiveKVResultCache.java:113)
> at
> org.apache.hadoop.hive.ql.exec.spark.HiveBaseFunctionResultList$ResultIterator.next(HiveBaseFunctionResultList.java:124)
> at
> org.apache.hadoop.hive.ql.exec.spark.HiveBaseFunctionResultList$ResultIterator.next(HiveBaseFunctionResultList.java:82)
> at
> scala.collection.convert.Wrappers$JIteratorWrapper.next(Wrappers.scala:42)
> at scala.collection.Iterator$class.foreach(Iterator.scala:727)
> at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
> at
> org.apache.spark.shuffle.hash.HashShuffleWriter.write(HashShuffleWriter.scala:65)
> at
> org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:68)
> at
> org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
> at org.apache.spark.scheduler.Task.run(Task.scala:54)
> at
> org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:199)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
> at java.lang.Thread.run(Thread.java:722)
> {noformat}
> Basically, the cause is that RowContainer is misused(it's not allowed to
> write once someone read row from it), i'm trying to figure out whether it's a
> hive issue or just in hive on spark mode.
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