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https://issues.apache.org/jira/browse/HDFS-10673?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15408501#comment-15408501
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Kihwal Lee commented on HDFS-10673:
-----------------------------------

Committed this to trunk and branch-2. Thanks for the reviews and feedback, 
[~jingzhao].

> Optimize FSPermissionChecker's internal path usage
> --------------------------------------------------
>
>                 Key: HDFS-10673
>                 URL: https://issues.apache.org/jira/browse/HDFS-10673
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: hdfs
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>         Attachments: HDFS-10673.1.patch, HDFS-10673.2.patch, HDFS-10673.patch
>
>
> The INodeAttributeProvider and AccessControlEnforcer features degrade 
> performance and generate excessive garbage even when neither is used.  Main 
> issues:
> # A byte[][] of components is unnecessarily created.  Each path component 
> lookup converts a subrange of the byte[][] to a new String[] - then not used 
> by default attribute provider.
> # Subaccess checks are insanely expensive.  The full path of every subdir is 
> created by walking up the inode tree, creating a INode[], building a string 
> by converting each inode's byte[] name to a string, etc.  Which will only be 
> used if there's an exception.
> The expensive of #1 should only be incurred when using the provider/enforcer 
> feature.  For #2, paths should be created on-demand for exceptions.



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