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https://issues.apache.org/jira/browse/KAFKA-3894?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jun Rao updated KAFKA-3894:
---------------------------
    Assignee: Tom Crayford

[~tcrayford-heroku], thanks for the patch. Filed a followup jira KAFKA-4072 to 
improve the memory usage in log cleaner.

> LogCleaner thread crashes if not even one segment can fit in the offset map
> ---------------------------------------------------------------------------
>
>                 Key: KAFKA-3894
>                 URL: https://issues.apache.org/jira/browse/KAFKA-3894
>             Project: Kafka
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 0.8.2.2, 0.9.0.1, 0.10.0.0
>         Environment: Oracle JDK 8
> Ubuntu Precise
>            Reporter: Tim Carey-Smith
>            Assignee: Tom Crayford
>              Labels: compaction
>             Fix For: 0.10.1.0
>
>
> The log-cleaner thread can crash if the number of keys in a topic grows to be 
> too large to fit into the dedupe buffer. 
> The result of this is a log line: 
> {quote}
> broker=0 pri=ERROR t=kafka-log-cleaner-thread-0 at=LogCleaner 
> \[kafka-log-cleaner-thread-0\], Error due to  
> java.lang.IllegalArgumentException: requirement failed: 9750860 messages in 
> segment MY_FAVORITE_TOPIC-2/00000000000047580165.log but offset map can fit 
> only 5033164. You can increase log.cleaner.dedupe.buffer.size or decrease 
> log.cleaner.threads
> {quote}
> As a result, the broker is left in a potentially dangerous situation where 
> cleaning of compacted topics is not running. 
> It is unclear if the broader strategy for the {{LogCleaner}} is the reason 
> for this upper bound, or if this is a value which must be tuned for each 
> specific use-case. 
> Of more immediate concern is the fact that the thread crash is not visible 
> via JMX or exposed as some form of service degradation. 
> Some short-term remediations we have made are:
> * increasing the size of the dedupe buffer
> * monitoring the log-cleaner threads inside the JVM



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