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https://issues.apache.org/jira/browse/HDFS-4461?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13687514#comment-13687514
]
Hudson commented on HDFS-4461:
------------------------------
Integrated in Hadoop-trunk-Commit #3975 (See
[https://builds.apache.org/job/Hadoop-trunk-Commit/3975/])
HDFS-4461. DirectoryScanner: volume prefix takes up memory for every block
that is scanned (Colin Patrick McCabe) (Revision 1494401)
Result = SUCCESS
cmccabe :
http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1494401
Files :
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DirectoryScanner.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/FsVolumeSpi.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsVolumeImpl.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDirectoryScanner.java
> DirectoryScanner: volume path prefix takes up memory for every block that is
> scanned
> -------------------------------------------------------------------------------------
>
> Key: HDFS-4461
> URL: https://issues.apache.org/jira/browse/HDFS-4461
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: 2.0.3-alpha
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Priority: Minor
> Attachments: HDFS-4461.002.patch, HDFS-4461.003.patch,
> HDFS-4461.004.patch, HDFS-4661.006.patch, memory-analysis.png
>
>
> In the {{DirectoryScanner}}, we create a class {{ScanInfo}} for every block.
> This object contains two File objects-- one for the metadata file, and one
> for the block file. Since those File objects contain full paths, users who
> pick a lengthly path for their volume roots will end up using an extra
> N_blocks * path_prefix bytes per block scanned. We also don't really need to
> store File objects-- storing strings and then creating File objects as needed
> would be cheaper. This would be a nice efficiency improvement.
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