[DISCUSS]Query performance Multiple and possible memory leaks

Posted by litao on Jan 16, 2019; 11:06am
URL: http://apache-carbondata-dev-mailing-list-archive.168.s1.nabble.com/DISCUSS-Query-performance-Multiple-and-possible-memory-leaks-tp73608.html

I did an experiment these two days.Insert thousands of batches of data into a
table use global_sort.I found that the first query use 4800s JDBC memery is
14GB;when first finish i do the second query immediately  use the same sql
"select count(*) from sameTable". The second query take 3700s and
the JDBC memery increase to 20GB,between first and second there is no other
insertion and query.see the LRU debug log we can see  like this:" Removed
entry from InMemory lru cache ::
hdfs://hacluster/user/hive/warehouse/carbon.store/x/xx_17910/Fact/Part0/Segment_2497/2497_1547575104816.carbonindexmerge
|
org.apache.carbondata.core.cache.CarbonLRUCache.removeKey(CarbonLRUCache.java:163)2"
maybe the LRU cache is remove from memery,beside there is not another query.
From these phenomena, it may be seen that there are several problems.
1）is there has memory leaks for the 14GB ->20GB memery use.(i have jmap dump file)
2）Can the logic of LRU be optimized?
3）Is it possible to concurrently load index Files to LRU Using thread pools



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