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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-13752) fs.Path stores file path in java.net.URI causes big memory waste
Date Thu, 01 Nov 2018 00:54:00 GMT

    [ https://issues.apache.org/jira/browse/HDFS-13752?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16670976#comment-16670976
] 

Hadoop QA commented on HDFS-13752:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue}  0m  0s{color} | {color:blue}
Docker mode activated. {color} |
| {color:red}-1{color} | {color:red} patch {color} | {color:red}  0m  8s{color} | {color:red}
HDFS-13752 does not apply to trunk. Rebase required? Wrong Branch? See https://wiki.apache.org/hadoop/HowToContribute
for help. {color} |
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|| Subsystem || Report/Notes ||
| JIRA Issue | HDFS-13752 |
| Console output | https://builds.apache.org/job/PreCommit-HDFS-Build/25405/console |
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> fs.Path stores file path in java.net.URI causes big memory waste
> ----------------------------------------------------------------
>
>                 Key: HDFS-13752
>                 URL: https://issues.apache.org/jira/browse/HDFS-13752
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: fs
>    Affects Versions: 2.7.6
>         Environment: Hive 2.1.1 and hadoop 2.7.6 
>            Reporter: Barnabas Maidics
>            Priority: Major
>         Attachments: HDFS-13752.001.patch, HDFS-13752.002.patch, HDFS-13752.003.patch,
HDFSbenchmark.pdf, Screen Shot 2018-07-20 at 11.12.38.png, heapdump-100000partitions.html,
measurement.pdf
>
>
> I was looking at HiveServer2 memory usage, and a big percentage of this was because
of org.apache.hadoop.fs.Path, where you store file paths in a java.net.URI object. The URI
implementation stores the same string in 3 different objects (see the attached image). In
Hive when there are many partitions this cause a big memory usage. In my particular case 42%
of memory was used by java.net.URI so it could be reduced to 14%. 
> I wonder if the community is open to replace it with a more memory efficient implementation
and what other things should be considered here? It can be a huge memory improvement for
Hadoop and for Hive as well.



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