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From "Vinayakumar B (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-7454) Reduce memory footprint for AclEntries in NameNode
Date Wed, 03 Dec 2014 06:56:12 GMT

     [ https://issues.apache.org/jira/browse/HDFS-7454?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Vinayakumar B updated HDFS-7454:
    Attachment: HDFS-7454-004.patch

Used the second option to cut direct access to entries array.

bq. Another question is that do we need to keep getEntries()? I just checked and it was called
in several places, but it might make sense to just fix them to the int-based APIs.
convertion of int array to ImmutableList<AclEntry> moved to {{AclStorage#getEntriesFromAclFeature}}.
This is currently referenced in only ACL modification APIs , such as creation, modify and
removal, and getAclStatus. I feel these are not frequent compared to just accessing the path.

> Reduce memory footprint for AclEntries in NameNode
> --------------------------------------------------
>                 Key: HDFS-7454
>                 URL: https://issues.apache.org/jira/browse/HDFS-7454
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>            Reporter: Vinayakumar B
>            Assignee: Vinayakumar B
>         Attachments: HDFS-7454-001.patch, HDFS-7454-002.patch, HDFS-7454-003.patch, HDFS-7454-004.patch
> HDFS-5620 indicated a GlobalAclSet containing unique {{AclFeature}} can be de-duplicated
to save the memory in NameNode. However it was not implemented at that time.
> This Jira re-proposes same implementation, along with de-duplication of unique {{AclEntry}}
across all ACLs.
> One simple usecase is:
> A mapreduce user's home directory with the set of default ACLs, under which lot of other
files/directories could be created when jobs is run. Here all the default ACLs of parent directory
will be duplicated till the explicit delete of those ACLs. With de-duplication,only one object
will be in memory for the same Entry across all ACLs of all files/directories.

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