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https://issues.apache.org/jira/browse/MAPREDUCE-2459?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13033350#comment-13033350
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Mac Yang commented on MAPREDUCE-2459:
-------------------------------------
Mahadev, thanks for the feedback, I have updated the patch to include the
following changes,
- Removed '_' from harMetaCache
- Added modification time stamp check and reparse the index files if necessary.
This is to address the case where the archive is overwritten in between two
reads from the same process
> Cache HAR filesystem metadata
> -----------------------------
>
> Key: MAPREDUCE-2459
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2459
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: harchive
> Reporter: Mac Yang
> Assignee: Mac Yang
> Fix For: 0.23.0
>
> Attachments: MAPREDUCE-2459.1.patch, MAPREDUCE-2459.2.patch
>
>
> Each HAR file system has two index files that contains information on how
> files are stored in the part files. During the block location calculation,
> these indexes are reread for every file in the archive. Caching the indexes
> and the status of the part files will greatly reduce the number of name node
> operations during the job setup time.
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