[jira] [Commented] (MAPREDUCE-6626) Reuse ObjectMapper instance in MapReduce

["Akira AJISAKA (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAPREDUCE-6626?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15139317#comment-15139317 ] 

Akira AJISAKA commented on MAPREDUCE-6626:
------------------------------------------

Committed this to trunk, branch-2, and branch-2.8. Thanks [~linyiqun] for creating patches and thanks [~brahmareddy] for the review.

> Reuse ObjectMapper instance in MapReduce
> ----------------------------------------
>
>                 Key: MAPREDUCE-6626
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6626
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: performance
>    Affects Versions: 2.7.1
>            Reporter: Lin Yiqun
>            Assignee: Lin Yiqun
>            Priority: Minor
>             Fix For: 2.8.0
>
>         Attachments: MAPREDUCE-6626.002.patch, MAPREDUCE-6626.003.patch, MAPREDUCE-6626.004.patch, MAPREDUCE.001.patch
>
>
> Now in MapReduce, there are some places creating a new ObjectMapper instance every time. In wiki of ObjectMapper, it suggested:
> {code}
> Further: it is beneficial to use just one instance (or small number of instances) for data binding; many optimizations for reuse (of symbol tables, some buffers) depend on ObjectMapper instances being reused. 
> {code}
> http://webcache.googleusercontent.com/search?q=cache:kybMTIJC6F4J:wiki.fasterxml.com/JacksonFAQ+&cd=4&hl=ja&ct=clnk&gl=jp, it's similar to HDFS-9724.



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