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https://issues.apache.org/jira/browse/KAFKA-15609?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17775725#comment-17775725
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Luke Chen commented on KAFKA-15609:
-----------------------------------

Wow, another edge case! Nice find!
So you mean, when a segment rolled, before the data flushed, the RSM is copying 
the incomplete segment/index into remote tier, right? Agree we should force 
flush before copying data. I've checked, if we flush the offset multiple times, 
only the 1st time will acquire lock and do real flush operation. So it won't 
increase overhead to CPU. 

> Corrupted index uploaded to remote tier
> ---------------------------------------
>
>                 Key: KAFKA-15609
>                 URL: https://issues.apache.org/jira/browse/KAFKA-15609
>             Project: Kafka
>          Issue Type: Bug
>          Components: Tiered-Storage
>    Affects Versions: 3.6.0
>            Reporter: Divij Vaidya
>            Priority: Minor
>
> While testing Tiered Storage, we have observed corrupt indexes being present 
> in remote tier. One such situation is covered here at 
> https://issues.apache.org/jira/browse/KAFKA-15401. This Jira presents another 
> such possible case of corruption.
> Potential cause of index corruption:
> We want to ensure that the file we are passing to RSM plugin contains all the 
> data which is present in MemoryByteBuffer i.e. we should have flushed the 
> MemoryByteBuffer to the file using force(). In Kafka, when we close a 
> segment, indexes are flushed asynchronously [1]. Hence, it might be possible 
> that when we are passing the file to RSM, the file doesn't contain flushed 
> data. Hence, we may end up uploading indexes which haven't been flushed yet. 
> Ideally, the contract should enforce that we force flush the content of 
> MemoryByteBuffer before we give the file for RSM. This will ensure that 
> indexes are not corrupted/incomplete.
> [1] 
> [https://github.com/apache/kafka/blob/4150595b0a2e0f45f2827cebc60bcb6f6558745d/core/src/main/scala/kafka/log/UnifiedLog.scala#L1613]
>  



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