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https://issues.apache.org/jira/browse/KAFKA-8522?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16905792#comment-16905792
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Jun Rao commented on KAFKA-8522:
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[~Yohan123]: For upgrade, we can roughly do the following. If the new code only
finds the old style checkpoint file, it uses that for the cleaning offsets.
Once the new checkpoint files have been written, the old checkpoint file can be
deleted. After that, the new code will be using the cleaning offsets in the new
checkpoint file.
> Tombstones can survive forever
> ------------------------------
>
> Key: KAFKA-8522
> URL: https://issues.apache.org/jira/browse/KAFKA-8522
> Project: Kafka
> Issue Type: Improvement
> Components: log cleaner
> Reporter: Evelyn Bayes
> Priority: Minor
>
> This is a bit grey zone as to whether it's a "bug" but it is certainly
> unintended behaviour.
>
> Under specific conditions tombstones effectively survive forever:
> * Small amount of throughput;
> * min.cleanable.dirty.ratio near or at 0; and
> * Other parameters at default.
> What happens is all the data continuously gets cycled into the oldest
> segment. Old records get compacted away, but the new records continuously
> update the timestamp of the oldest segment reseting the countdown for
> deleting tombstones.
> So tombstones build up in the oldest segment forever.
>
> While you could "fix" this by reducing the segment size, this can be
> undesirable as a sudden change in throughput could cause a dangerous number
> of segments to be created.
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