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From "Jing Zhao (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-4372) Track NameNode startup progress
Date Tue, 11 Jun 2013 06:48:24 GMT

    [ 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:
---------------------------------

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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