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https://issues.apache.org/jira/browse/KAFKA-7297?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16722342#comment-16722342
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Ismael Juma commented on KAFKA-7297:
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Another way to handle this is for mutating operations to update a copy and then
atomically update the collection. That's generally a better pattern when
mutations are rare compared to reads.
> Both read/write access to Log.segments should be protected by lock
> ------------------------------------------------------------------
>
> Key: KAFKA-7297
> URL: https://issues.apache.org/jira/browse/KAFKA-7297
> Project: Kafka
> Issue Type: Improvement
> Reporter: Dong Lin
> Assignee: Zhanxiang (Patrick) Huang
> Priority: Major
>
> Log.replaceSegments() updates segments in two steps. It first adds new
> segments and then remove old segments. Though this operation is protected by
> a lock, other read access such as Log.logSegments does not grab lock and thus
> these methods may return an inconsistent view of the segments.
> As an example, say Log.replaceSegments() intends to replace segments [0,
> 100), [100, 200) with a new segment [0, 200). In this case if Log.logSegments
> is called right after the new segments are added, the method may return
> segments [0, 200), [100, 200) and messages in the range [100, 200) may be
> duplicated if caller choose to enumerate all messages in all segments
> returned by the method.
> The solution is probably to protect read/write access to Log.segments with
> read/write lock.
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