[
https://issues.apache.org/jira/browse/HADOOP-16090?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16762281#comment-16762281
]
Dmitri Chmelev commented on HADOOP-16090:
-----------------------------------------
Ok, sounds good. I'll send the patch that performs HEAD checks on upwalks
during cleanup for versioned buckets.
The rest of the fix that requires operation context can go into 3.x, since we
ran into the problem while using Flink 1.6.2 and are thinking of upgrading
Flink, and the last time I checked Flink 1.7.1 already uses Hadoop 3.1.0.
> deleteUnnecessaryFakeDirectories() creates unnecessary delete markers in a
> versioned S3 bucket
> ----------------------------------------------------------------------------------------------
>
> Key: HADOOP-16090
> URL: https://issues.apache.org/jira/browse/HADOOP-16090
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 2.8.1
> Reporter: Dmitri Chmelev
> Priority: Minor
>
> The fix to avoid calls to getFileStatus() for each path component in
> deleteUnnecessaryFakeDirectories() (HADOOP-13164) results in accumulation of
> delete markers in versioned S3 buckets. The above patch replaced
> getFileStatus() checks with a single batch delete request formed by
> generating all ancestor keys formed from a given path. Since the delete
> request is not checking for existence of fake directories, it will create a
> delete marker for every path component that did not exist (or was previously
> deleted). Note that issuing a DELETE request without specifying a version ID
> will always create a new delete marker, even if one already exists ([AWS S3
> Developer
> Guide|https://docs.aws.amazon.com/AmazonS3/latest/dev/RemDelMarker.html])
> Since deleteUnnecessaryFakeDirectories() is called as a callback on
> successful writes and on renames, delete markers accumulate rather quickly
> and their rate of accumulation is inversely proportional to the depth of the
> path. In other words, directories closer to the root will have more delete
> markers than the leaves.
> This behavior negatively impacts performance of getFileStatus() operation
> when it has to issue listObjects() request (especially v1) as the delete
> markers have to be examined when the request searches for first current
> non-deleted version of an object following a given prefix.
> I did a quick comparison against 3.x and the issue is still present:
> [https://github.com/apache/hadoop/blob/trunk/hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java#L2947|https://github.com/apache/hadoop/blob/trunk/hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java#L2947]
>
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
