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https://issues.apache.org/jira/browse/FLINK-10963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16701723#comment-16701723
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ASF GitHub Bot commented on FLINK-10963:
----------------------------------------

igalshilman commented on a change in pull request #7161: 
[FLINK-10963][fs-connector, s3] Cleanup tmp S3 objects uploaded as backups of 
in-progress files.
URL: https://github.com/apache/flink/pull/7161#discussion_r237019573
 
 

 ##########
 File path: 
flink-filesystems/flink-s3-fs-base/src/main/java/org/apache/flink/fs/s3/common/writer/RecoverableMultiPartUploadImpl.java
 ##########
 @@ -209,6 +204,10 @@ static String incompleteObjectNamePrefix(String 
objectName) {
                return parent + (child.isEmpty() ? "" : '_') + child + "_tmp_";
        }
 
+       private String createIncompletePartObjectName() {
+               return namePrefixForTempObjects + UUID.randomUUID().toString();
 
 Review comment:
   I'm wondering here why do we use `UUID` here, would that be possible to 
create the name deterministically as a function of the current jobid, attempt 
id, checkpoint id and the `namePrefixForTempObjects`?
   (unless they are not accessible at that level of abstraction)
   Having the name deterministic seems like a good building block to address 
the limitation described in this PR description.

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> Cleanup small objects uploaded to S3 as independent objects
> -----------------------------------------------------------
>
>                 Key: FLINK-10963
>                 URL: https://issues.apache.org/jira/browse/FLINK-10963
>             Project: Flink
>          Issue Type: Sub-task
>          Components: filesystem-connector
>    Affects Versions: 1.7.0
>            Reporter: Kostas Kloudas
>            Assignee: Kostas Kloudas
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.7.1
>
>
> The S3 {{RecoverableWriter}} uses the Multipart Upload (MPU) Feature of S3 in 
> order to upload the different part files. This means that a large part is 
> split in chunks of at least 5MB which are uploaded independently, whenever 
> each one of them is ready.
> This 5MB minimum size requires special handling of parts that are less than 
> 5MB when a checkpoint barrier arrives. These small files are uploaded as 
> independent objects (not associated with an active MPU). This way, when Flink 
> needs to restore, it simply downloads them and resumes writing to them.
> These small objects are currently not cleaned up, thus leading to wasted 
> space on S3.



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