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Posted to common-issues@hadoop.apache.org by "Vishwajeet Dusane (JIRA)" <ji...@apache.org> on 2016/03/03 12:25:18 UTC
[jira] [Commented] (HADOOP-12876) [Azure Data Lake] Support for
process level FileStatus cache to optimize GetFileStatus frequent opeations
[ https://issues.apache.org/jira/browse/HADOOP-12876?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15177700#comment-15177700 ]
Vishwajeet Dusane commented on HADOOP-12876:
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* 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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