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https://issues.apache.org/jira/browse/HIVE-18301?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16304359#comment-16304359
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liyunzhang commented on HIVE-18301:
-----------------------------------
[~lirui]:
{quote}
My understanding is these information will be lost if the HadoopRDD is cached.
{quote}
You mean that HadoopRDD will not store the spark plan? If yes, actually in
hive, it stores the spark plan on a file on hdfs and deserialize and serialize
from the file. See more code in
hive/ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java#getBaseWork. If
not, please spend more time to explain detail.
Here my question is that is there any other reason to disable MapInput#cache
besides avoiding multi-insert cases which there is union operator after
{{from}}
{code}
from (select * from dec union all select * from dec2) s
insert overwrite table dec3 select s.name, sum(s.value) group by s.name
insert overwrite table dec4 select s.name, s.value order by s.value;
{code}
If there is no other reason to disable MapInput# cache, I guess for
HIVE-17486, we can enable MapInput cache because HIVE-17486 is merge same
single table. There is few case like above ( from (select A union B) ....).
> Investigate to enable MapInput cache in Hive on Spark
> -----------------------------------------------------
>
> Key: HIVE-18301
> URL: https://issues.apache.org/jira/browse/HIVE-18301
> Project: Hive
> Issue Type: Bug
> Reporter: liyunzhang
> Assignee: liyunzhang
>
> Before IOContext problem is found in MapTran when spark rdd cache is enabled
> in HIVE-8920.
> so we disabled rdd cache in MapTran at
> [SparkPlanGenerator|https://github.com/kellyzly/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/exec/spark/SparkPlanGenerator.java#L202].
> The problem is IOContext seems not initialized correctly in the spark yarn
> client/cluster mode and caused the exception like
> {code}
> Job aborted due to stage failure: Task 93 in stage 0.0 failed 4 times, most
> recent failure: Lost task 93.3 in stage 0.0 (TID 616, bdpe48):
> java.lang.RuntimeException: Error processing row:
> java.lang.NullPointerException
> at
> org.apache.hadoop.hive.ql.exec.spark.SparkMapRecordHandler.processRow(SparkMapRecordHandler.java:165)
> at
> org.apache.hadoop.hive.ql.exec.spark.HiveMapFunctionResultList.processNextRecord(HiveMapFunctionResultList.java:48)
> at
> org.apache.hadoop.hive.ql.exec.spark.HiveMapFunctionResultList.processNextRecord(HiveMapFunctionResultList.java:27)
> at
> org.apache.hadoop.hive.ql.exec.spark.HiveBaseFunctionResultList.hasNext(HiveBaseFunctionResultList.java:85)
> at
> scala.collection.convert.Wrappers$JIteratorWrapper.hasNext(Wrappers.scala:42)
> at
> org.apache.spark.shuffle.sort.BypassMergeSortShuffleWriter.write(BypassMergeSortShuffleWriter.java:125)
> at
> org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:79)
> at
> org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:47)
> at org.apache.spark.scheduler.Task.run(Task.scala:85)
> at org.apache.spark.executor.Executor$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)
> Caused by: java.lang.NullPointerException
> at
> org.apache.hadoop.hive.ql.exec.AbstractMapOperator.getNominalPath(AbstractMapOperator.java:101)
> at
> org.apache.hadoop.hive.ql.exec.MapOperator.cleanUpInputFileChangedOp(MapOperator.java:516)
> at
> org.apache.hadoop.hive.ql.exec.Operator.cleanUpInputFileChanged(Operator.java:1187)
> at
> org.apache.hadoop.hive.ql.exec.MapOperator.process(MapOperator.java:546)
> at
> org.apache.hadoop.hive.ql.exec.spark.SparkMapRecordHandler.processRow(SparkMapRecordHandler.java:152)
> ... 12 more
> Driver stacktrace:
> {code}
> in yarn client/cluster mode, sometimes
> [ExecMapperContext#currentInputPath|https://github.com/kellyzly/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/exec/mr/ExecMapperContext.java#L109]
> is null when rdd cach is enabled.
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