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https://issues.apache.org/jira/browse/HDFS-5096?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13797122#comment-13797122
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Colin Patrick McCabe commented on HDFS-5096:
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bq. hdfs-default.xml: Let's document
dfs.namenode.path.based.cache.refresh.interval.ms.
Added.
bq. IntrusiveCollection#addFirst: This method appears to be only called from
test code. Do you want to keep it, or is it better to delete it?
It's a pretty small function. I'd like to keep it in case it's needed later.
Since we have a doubly-linked list, being able to add at the beginning or the
end is a nice feature.
bq. TestPathBasedCacheRequests#waitForCachedBlocks: This is another spot where
I think we should use GenericTestUtils#waitFor. Even though the JUnit-level
timeouts would abort, this tends to leave the process hanging around.
GenericTestUtils#waitFor would throw and exit more cleanly.
Good idea.
> Automatically cache new data added to a cached path
> ---------------------------------------------------
>
> Key: HDFS-5096
> URL: https://issues.apache.org/jira/browse/HDFS-5096
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode, namenode
> Reporter: Andrew Wang
> Assignee: Colin Patrick McCabe
> Attachments: HDFS-5096-caching.005.patch,
> HDFS-5096-caching.006.patch, HDFS-5096-caching.009.patch,
> HDFS-5096-caching.010.patch, HDFS-5096-caching.011.patch,
> HDFS-5096-caching.012.patch
>
>
> For some applications, it's convenient to specify a path to cache, and have
> HDFS automatically cache new data added to the path without sending a new
> caching request or a manual refresh command.
> One example is new data appended to a cached file. It would be nice to
> re-cache a block at the new appended length, and cache new blocks added to
> the file.
> Another example is a cached Hive partition directory, where a user can drop
> new files directly into the partition. It would be nice if these new files
> were cached.
> In both cases, this automatic caching would happen after the file is closed,
> i.e. block replica is finalized.
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