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https://issues.apache.org/jira/browse/HDFS-7454?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14229443#comment-14229443
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Vinayakumar B commented on HDFS-7454:
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Thanks [~cnauroth] and [~wheat9] for suggestions.
I could see that {{AclEntry}} is being stored as an {{int}} in FsImage
protobuf. I think same we could re-use or use similar to
{{INodeWithAdditionalFields#PermissionStatusFormat}} to pack AclEntry to an
32-bit {{int}}.
Packing {{AclEntry}} to {{int}} may be good option than de-duplication of
{{AclEntry}}. But as Chris already mentioned, may not resolve the duplication
of {{AclFeature}}.
How about combining these 2 options?
> Implement Global ACL Set for memory optimization 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-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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