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https://issues.apache.org/jira/browse/HADOOP-10987?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kihwal Lee updated HADOOP-10987:
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Attachment: HADOOP-10987.patch
The patch adds {{listStatusIterator()}} to {{FileSystem}} and implement it in
{{DistributedFileSystem}}.
It also fixing incomplete symlink handling in {{listLocatedStatus()}}. It was
discovered when testing the patch by plugging in the iterator based method for
all types of {{listStatus}} methods. The old code only works when the last
component of target path is a symlink. If a link or reserved name appears in
the middle, the method does not work.
The new {{listStatusIterator()}} method is covered in the basic fs test cases
by removing the fake wrapper in {{FileSystemTestWrapper}}. The chunked listing
is tested in {{TestFileStatus}}.
> Provide an iterator-based listing API for FileSystem
> ----------------------------------------------------
>
> Key: HADOOP-10987
> URL: https://issues.apache.org/jira/browse/HADOOP-10987
> Project: Hadoop Common
> Issue Type: Improvement
> Reporter: Kihwal Lee
> Attachments: HADOOP-10987.patch
>
>
> Iterator based listing methods already exist in {{FileContext}} for both
> simple listing and listing with locations. However, {{FileSystem}} lacks the
> former. From what I understand, it wasn't added to {{FileSystem}} because it
> was believed to be phased out soon. Since {{FileSystem}} is very well alive
> today and new features are getting added frequently, I propose adding an
> iterator based {{listStatus}} method. As for the name of the new method, we
> can use the same name used in {{FileContext}} : {{listStatusIterator()}}.
> It will be particularly useful when listing giant directories. Without this,
> the client has to build up a huge data structure and hold it in memory. We've
> seen client JVMs running out of memory because of this.
> Once this change is made, we can modify FsShell, etc. in followup jiras.
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