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https://issues.apache.org/jira/browse/HADOOP-16430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16914182#comment-16914182
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Steve Loughran commented on HADOOP-16430:
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Highlight: coding this has thrown up an issue with the current implementation.
the recursive delete only asks S3 for files, not DDB.
This ensures that incomplete DDB stores are not a problem, so that deletion
does mostly recover from any problems. However, it relies on LIST being
complete, which we know is untrue as it is eventually consistent.
Proposed: after deleting all files, we do a recursive list of what is left in
S3Guard and delete those too. That way files we know about but which the list
missed will still get cleaned up.
> S3AFilesystem.delete to incrementally update s3guard with deletions
> -------------------------------------------------------------------
>
> Key: HADOOP-16430
> URL: https://issues.apache.org/jira/browse/HADOOP-16430
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 3.2.0, 3.3.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Major
> Attachments: Screenshot 2019-07-16 at 22.08.31.png
>
>
> Currently S3AFilesystem.delete() only updates the delete at the end of a
> paged delete operation. This makes it slow when there are many thousands of
> files to delete ,and increases the window of vulnerability to failures
> Preferred
> * after every bulk DELETE call is issued to S3, queue the (async) delete of
> all entries in that post.
> * at the end of the delete, await the completion of these operations.
> * inside S3AFS, also do the delete across threads, so that different HTTPS
> connections can be used.
> This should maximise DDB throughput against tables which aren't IO limited.
> When executed against small IOP limited tables, the parallel DDB DELETE
> batches will trigger a lot of throttling events; we should make sure these
> aren't going to trigger failures
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