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https://issues.apache.org/jira/browse/HDFS-4372?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13680253#comment-13680253
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Jing Zhao commented on HDFS-4372:
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Thanks for the responses Chris!
bq. I wrote all of this code before snapshots, so I'll take a look to see if
there is something more reasonable to do now that snapshots are in trunk.
The main challenge here is that after renaming with snapshots, for the same
subtree, we count in the number of snapshot diffs for namespace quota usage
when the subtree is referenced by a DstReference node (which means the subtree
is included in the current tree); but we do not count the snapshot diffs when
we come from a WithName node. In such case, it is difficult to decide whether
we need to increment the counter (and the value of the increment) after loading
an inode from the fsimage.
bq. I added the check for containsKey to limit the impact of that. Maybe it's
just a minor optimization, but considering that these methods could be called
in tight loops during startup, I wanted to keep it under control.
This makes sense to me. Thanks a lot for the explanation.
bq. By switching to primitive long with -1 reserved for "uninitialized", is the
intent to reduce memory footprint of a boxed Long? If so, then I definitely can
make that change.
Yes. Thanks!
> Track NameNode startup progress
> -------------------------------
>
> Key: HDFS-4372
> URL: https://issues.apache.org/jira/browse/HDFS-4372
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Affects Versions: 3.0.0
> Reporter: Chris Nauroth
> Assignee: Chris Nauroth
> Attachments: HDFS-4372.1.patch
>
>
> Track detailed progress information about the steps of NameNode startup to
> enable display to users.
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