zhao jintao created KYLIN-3899:
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Summary: 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
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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