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Sergio Peña commented on HIVE-16166: ------------------------------------ Thanks. As you mentioned, this is a performance optimization, and if it does not work for some reason, then we can still rely on the normal way without using intern strings. +1 Let's wait for HiveQA. > HS2 may still waste up to 15% of memory on duplicate strings > ------------------------------------------------------------ > > Key: HIVE-16166 > URL: https://issues.apache.org/jira/browse/HIVE-16166 > Project: Hive > Issue Type: Improvement > Reporter: Misha Dmitriev > Assignee: Misha Dmitriev > Attachments: ch_2_excerpt.txt, HIVE-16166.01.patch, > HIVE-16166.02.patch > > > A heap dump obtained from one of our users shows that 15% of memory is wasted > on duplicate strings, despite the recent optimizations that I made. The > problematic strings just come from different sources this time. See the > excerpt from the jxray (www.jxray.com) analysis attached. > Adding String.intern() calls in the appropriate places reduces the overhead > of duplicate strings with this workload to ~6%. The remaining duplicates come > mostly from JDK internal and MapReduce data structures, and thus are more > difficult to fix. -- This message was sent by Atlassian JIRA (v6.3.15#6346)