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https://issues.apache.org/jira/browse/HIVE-17407?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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liyunzhang_intel updated HIVE-17407:
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Attachment: explain.65
hang.PNG
> TPC-DS/query65 hangs on HoS in certain settings
> -----------------------------------------------
>
> Key: HIVE-17407
> URL: https://issues.apache.org/jira/browse/HIVE-17407
> Project: Hive
> Issue Type: Bug
> Reporter: liyunzhang_intel
> Attachments: explain.65, hang.PNG
>
>
> [TPC-DS/query65.sql|https://github.com/kellyzly/hive-testbench/blob/hive14/sample-queries-tpcds/query65.sql]
> hangs when using following settings on 3TB scale.
> {code}
> set hive.auto.convert.join.noconditionaltask.size=3000000;
> {code}
> the explain is attached in explain65. The screenshot shows that it hanged
> in the Stage5.
> Let's explain why hang.
> {code}
> Reducer 10 <- Map 9 (GROUP, 1009)
> Reducer 2 <- Map 1 (PARTITION-LEVEL SORT, 1), Map 5 (PARTITION-LEVEL
> SORT, 1), Reducer 7 (PARTITION-LEVEL SORT, 1)
> Reducer 3 <- Reducer 10 (PARTITION-LEVEL SORT, 1009), Reducer 2
> (PARTITION-LEVEL SORT, 1009)
> Reducer 4 <- Reducer 3 (SORT, 1)
> Reducer 7 <- Map 6 (GROUP PARTITION-LEVEL SORT, 1009)
> {code}
> The numPartitions of SparkEdgeProperty which connects Reducer 2 and Reducer 3
> is 1. This is because
> org.apache.hadoop.hive.ql.parse.spark.GenSparkUtils#createReduceWork
> {code}
> public ReduceWork createReduceWork(GenSparkProcContext context, Operator<?>
> root,
> SparkWork sparkWork) throws SemanticException {
>
> for (Operator<? extends OperatorDesc> parentOfRoot :
> root.getParentOperators()) {
> Preconditions.checkArgument(parentOfRoot instanceof ReduceSinkOperator,
> "AssertionError: expected parentOfRoot to be an "
> + "instance of ReduceSinkOperator, but was "
> + parentOfRoot.getClass().getName());
> ReduceSinkOperator reduceSink = (ReduceSinkOperator) parentOfRoot;
> maxExecutors = Math.max(maxExecutors,
> reduceSink.getConf().getNumReducers());
> }
> reduceWork.setNumReduceTasks(maxExecutors);
> {code}
> here the numReducers of all parentOfRoot is 1( in the explain, the
> parallelism of Map 1, Map 5, Reducer 7 is 1), so the numPartitions of
> SparkEdgeProperty which connects Reducer 2 and Reducer 3 is 1.
> More explain why the parallelism of Map 1, Map 5,Reducer 7 are 1. The
> physical plan of the query is
> {code}
> TS[0]-FIL[50]-RS[2]-JOIN[5]-FIL[49]-SEL[7]-GBY[8]-RS[9]-GBY[10]-SEL[11]-GBY[15]-SEL[16]-RS[33]-JOIN[34]-RS[36]-JOIN[39]-FIL[48]-SEL[41]-RS[42]-SEL[43]-LIM[44]-FS[45]
> TS[1]-FIL[51]-RS[4]-JOIN[5]
> TS[17]-FIL[53]-RS[19]-JOIN[22]-FIL[52]-SEL[24]-GBY[25]-RS[26]-GBY[27]-RS[38]-JOIN[39]
> TS[18]-FIL[54]-RS[21]-JOIN[22]
> TS[29]-FIL[55]-RS[31]-JOIN[34]
> TS[30]-FIL[56]-RS[32]-JOIN[34]
> {code}
> The related RS of Map1, Map5, Reducer 7 is RS\[31\], RS\[32\], RS\[33\]. The
> parallelism is set by
> [SemanticAnalyzer#genJoinReduceSinkChild|https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java#L8267]
> It seems that there is no logical error in the code. But it is not reasonable
> to use 1 task to execute to deal with so big data(more than 30GB). Is there
> any way to pass the query in this situation( the reason why i set
> hive.auto.convert.join.noconditionaltask.size as 3000000, if the join is
> converted to the map join, it will throw disk error).
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