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https://issues.apache.org/jira/browse/FLINK-10963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16701817#comment-16701817
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ASF GitHub Bot commented on FLINK-10963:
----------------------------------------
kl0u 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_r237062852
##########
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:
This `UUID` was added in an effort to add entropy to the paths/objects
uploaded to S3. I agree that any randomness, makes cleaning up more difficult
but I think this discussion fits better to the JIRA that will handle the
general cleaning up of left-over temporary files/objects.
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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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