[jira] [Resolved] (PARQUET-1261) Parquet-format interns strings when reading filemetadata

["Robert Kruszewski (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PARQUET-1261?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Robert Kruszewski resolved PARQUET-1261.
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    Resolution: Not A Problem

This isn't really a parquet issue - after thorough investigation it's clear that interning is the best way to save space. It's only CMS that has bad time dealing with it

> Parquet-format interns strings when reading filemetadata
> --------------------------------------------------------
>
>                 Key: PARQUET-1261
>                 URL: https://issues.apache.org/jira/browse/PARQUET-1261
>             Project: Parquet
>          Issue Type: Bug
>    Affects Versions: 1.9.0
>            Reporter: Robert Kruszewski
>            Assignee: Robert Kruszewski
>            Priority: Major
>              Labels: pull-request-available
>
> Parquet-format when deserializing metadata will intern strings. References I could find suggested that it had been done to reduce memory pressure early on. Java (and jvm in particular) went a long way since then and interning is generally discouraged, see [https://shipilev.net/jvm-anatomy-park/10-string-intern/] for a good explanation. What is more since java 8 there's string deduplication implemented at GC level per [http://openjdk.java.net/jeps/192.] During our usage and testing we found the interning to cause significant gc pressure for long running applications due to bigger GC root set.
> This issue proposes removing interning given it's questionable whether it should be used in modern jvms.



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