Daryn Sharp created HDFS-10673:
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             Summary: 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


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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