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https://issues.apache.org/jira/browse/HADOOP-16380?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16880368#comment-16880368
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Steve Loughran commented on HADOOP-16380:
-----------------------------------------
Note comment in {{org.apache.hadoop.fs.s3a.ITestS3GuardEmptyDirs}}
{code}
/**
* Test logic around whether or not a directory is empty, with S3Guard enabled.
* The fact that S3AFileStatus has an isEmptyDirectory flag in it makes caching
* S3AFileStatus's really tricky, as the flag can change as a side effect of
* changes to other paths.
* After S3Guard is merged to trunk, we should try to remove the
* isEmptyDirectory flag from S3AFileStatus, or maintain it outside
* of the MetadataStore.
*/
{code}
> S3Guard tombstones can mislead about directory empty status
> -----------------------------------------------------------
>
> Key: HADOOP-16380
> URL: https://issues.apache.org/jira/browse/HADOOP-16380
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3, test
> Affects Versions: 3.2.0, 3.0.3, 3.3.0, 3.1.2
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Critical
>
> If S3AFileSystem does an S3 LIST restricted to a single object to see if a
> directory is empty, and the single entry found has a tombstone marker (either
> from an inconsistent DDB Table or from an eventually consistent LIST) then it
> will consider the directory empty, _even if there is 1+ entry which is not
> deleted_
> We need to make sure the calculation of whether a directory is empty or not
> is resilient to this, efficiently.
> It surfaces as an issue two places
> * delete(path) (where it may make things worse)
> * rename(src, dest), where a check is made for dest != an empty directory.
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