[jira] [Closed] (KYLIN-3899) Kylin throws OutOfMemory exception during the sql query

["zhao jintao (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KYLIN-3899?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

zhao jintao closed KYLIN-3899.
------------------------------
       Resolution: Fixed
    Fix Version/s: v3.0.0-alpha
                   v2.6.2

已在此版本修复；[https://issues.apache.org/jira/projects/KYLIN/issues/KYLIN-3797?filter=allissues]

> Kylin throws OutOfMemory exception during the sql query 
> --------------------------------------------------------
>
>                 Key: KYLIN-3899
>                 URL: https://issues.apache.org/jira/browse/KYLIN-3899
>             Project: Kylin
>          Issue Type: Bug
>          Components: Query Engine
>    Affects Versions: v2.5.2
>         Environment: Huawei FusionInsight
>            Reporter: zhao jintao
>            Priority: Major
>             Fix For: v2.6.2, v3.0.0-alpha
>
>   Original Estimate: 672h
>  Remaining Estimate: 672h
>
> Hi team:
> I use Tableau+Kylin in my OLAP system.
>  But Kylin sometimes throws an OutOfMemory exception and then crashed.
> I find "OutOfMemoryError info" in kylin.log:
> {quote}java.lang.OutOfMemoryError: Java heap space
> Dumping heap to java_pid24217.hprof ...
> #
> #  java.lang.OutOfMemoryError: Java heap space
> #  -XX:OutOfMemoryError="kill -9 %p"
> #    Executing /bin/sh -c "kill -9 24217" ... 
> Java HotSpot(TM) 64-Bit Server VM warning:ignoring option MaxPermSize=512m; support was removed in 8.0
> Java HotSpot(TM) 64-Bit Server VM warning:Using incremental CMS is deprecated and will likely be removed in a future release.
> {quote}
> Then I use Memory Analyzer to analysis dump file. I find that all most of memory is occupied by a Tableau sql query thread, that query uses 23.4G memory, 99% of all mepory.
>  
> I find that query thread has a big linkedlist uses  19.7G memory, this linkedlist has LogicalTupleFilter entity,  contains 43497028 entries.
>  
> Then I find that the crash stack as these:
> {quote}at org.apache.kylin.metadata.filter.LogicalTupleFilter.copy()Lorg/apache/kylin/metadata/filter/TupleFilter; (LogicalTupleFilter.java 55)
> at org.apache.kylin.metadata.filter.TupleFilter.cartesianProduct(Ljava/util/List:Lorg/apache/kylin/metadata/filter/TupleFilter:)Ljava/util/List: (TupleFilter.java:279)
> at org.apache.kylin.metadata.filter.TupleFilter.flattenInternal(Lorg/apache/kylin/metadata/filter/TupleFilter:)Lorg/apache/kylin/metadata/filter/TupleFilter: (TupleFilter.java:252)
> at org.apache.kylin.metadata.filter.TupleFilter.flatFilter()Lorg/apache/kylin/metadata/filter/TupleFilter: (TupleFilter.java:218)
> at org.apache.kylin.cube.gridtable.ScanrangePlannerBase.flattenToOrAndFilter(Lorg/apache/kylin/metadata/filter/TupleFilter:)Lorg/apache/kylin/metadata/filter/TupleFilter: (ScanRangePlannerBase.java:73)
> at org.apache.kylin.storage.gtrecord.CubeScanRangePlanner.planScanRanges()Ljava/util/List; (CubeScanRangePlanner.java:216)
> ......
> {quote}
>  
> I find that Kylin's SQL query statement which is generated by Tableau is very complex. The length of SQL query statement is 54836, with "IN", "NOT IN", multi-level "OR", "AND" conditions and group by filtering.
>  
> Have other users ever had this problem?
>  
> Best Regards.
> Thanks.
>  
> Zhao Jintao.
>  
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