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From "Lin Yiqun (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-6626) Reuse objectMapper instance in MapReduce
Date Mon, 08 Feb 2016 08:47:39 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-6626?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15136711#comment-15136711

Lin Yiqun commented on MAPREDUCE-6626:

The test are all passed. The patch looks fine to the current code, can you review patch again,

> 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
>         Attachments: MAPREDUCE-6626.002.patch, MAPREDUCE-6626.003.patch, MAPREDUCE-6626.004.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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