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https://issues.apache.org/jira/browse/HADOOP-15550?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16520740#comment-16520740
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Xiao Chen commented on HADOOP-15550:
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Thanks Todd and Steve. Latest patch looks great!
Sorry for the nit, {{WRITER}} and {{MAP_READER}} could be final (seem to recall
checkstyle should complain that, not sure why it doesn't this time). +1 from me
pending that.
> Avoid static initialization of ObjectMappers
> --------------------------------------------
>
> Key: HADOOP-15550
> URL: https://issues.apache.org/jira/browse/HADOOP-15550
> Project: Hadoop Common
> Issue Type: Bug
> Components: performance
> Affects Versions: 3.2.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Minor
> Attachments: hadoop-15550.txt, hadoop-15550.txt, hadoop-15550.txt,
> hadoop-15550.txt
>
>
> Various classes statically initialize an ObjectMapper READER instance. This
> ends up doing a bunch of class-loading of Jackson libraries that can add up
> to a fair amount of CPU, even if the reader ends up not being used. This is
> particularly the case with WebHdfsFileSystem, which is class-loaded by a
> serviceloader even when unused in a particular job. We should lazy-init these
> members instead of doing so as a static class member.
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