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https://issues.apache.org/jira/browse/HADOOP-12876?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15177700#comment-15177700
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Vishwajeet Dusane commented on HADOOP-12876:
--------------------------------------------
* FileStatus cache is simple process level cache which mirrors backend storage
FileStatus objects.
* Time to live on the FileStatus cached object is limited. 5 seconds default
and configurable through core-site.xml
* FileStatus objects are stored in Synchronized LinkedHashMap. Where key is
fully qualified file path and value is FileStatus java object along with time
to live information.
* FileStatus cache is built based on successful responses to GetFileStatus and
ListStatus calls for existing files/folders. Non existent files/folder are not
maintained in the cache.
* FileStatus cache motivation is to avoid multiple GetFileStatus calls to the
ADL backend and as a result gain better performance for job startup and during
execution.
> [Azure Data Lake] Support for process level FileStatus cache to optimize
> GetFileStatus frequent opeations
> ---------------------------------------------------------------------------------------------------------
>
> Key: HADOOP-12876
> URL: https://issues.apache.org/jira/browse/HADOOP-12876
> Project: Hadoop Common
> Issue Type: New Feature
> Components: fs, fs/azure, tools
> Reporter: Vishwajeet Dusane
> Assignee: Vishwajeet Dusane
>
> Add support to cache GetFileStatus and ListStatus response locally for
> limited period of time. Local cache for limited period of time would optimize
> number of calls for GetFileStatus operation.
> One of the example where local limited period cache would be useful -
> terasort ListStatus on input directory follows with GetFileStatus operation
> on each file within directory. For 2048 input files in a directory would save
> 2048 GetFileStatus calls during start up (Using the ListStatus response to
> cache FileStatus instances).
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