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https://issues.apache.org/jira/browse/HDFS-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13144522#comment-13144522
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Tsz Wo (Nicholas), SZE commented on HDFS-2246:
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- For DataNode.getBlockLocalPathInfo(..),
-* DataNode should check DFS_CLIENT_READ_SHORTCIRCUIT.
-* Should it calls checkBlockToken?
-* Should it checks whether the client address is local?
- DataNode.getBlockLocalPathInfo(..) is not supposed to calls
FSDataset.getMetaFile(..) directly. It should only calls FSDatasetInterface
methods. How about change the new FSDatasetInterface.getBlockFile(..) to
getBlockLocalPathInfo(..) wich returns BlockLocalPathInfo?
- Change DataNode.userWithLocalPathAccess to final.
- SoftLRUCache is implemented with SoftReference values. In general, it is a
useful data structure. However, it may not be useful here since the size of
the cache is about 10k and the size of value is small (< 1k). I suggest using
a synchronized LinkedHashMap (no SoftReference) in BlockReaderLocal.cache and
remove SoftLRUCache from the patch.
- BlockReaderLocal.cache should not be initialized if checkShortCircuit is not
enabled.
I have not yet finished reading the client code.
> Shortcut a local client reads to a Datanodes files directly
> -----------------------------------------------------------
>
> Key: HDFS-2246
> URL: https://issues.apache.org/jira/browse/HDFS-2246
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Sanjay Radia
> Attachments: 0001-HDFS-347.-Local-reads.patch,
> HDFS-2246-branch-0.20-security-205.patch,
> HDFS-2246-branch-0.20-security-205.patch,
> HDFS-2246-branch-0.20-security.patch, HDFS-2246.20s.1.patch,
> HDFS-2246.20s.2.txt, HDFS-2246.20s.3.txt, HDFS-2246.20s.4.txt,
> HDFS-2246.20s.patch, localReadShortcut20-security.2patch
>
>
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