[jira] [Commented] (KAFKA-3894) Log Cleaner thread crashes and never restarts

["Peter Davis (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-3894?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15360062#comment-15360062 ] 

Peter Davis commented on KAFKA-3894:
------------------------------------

A quick improvement would be to increase the severity of the log message when log cleaner stops. Right now there is just an "INFO" message that's easy to miss.

> Log Cleaner thread crashes and never restarts
> ---------------------------------------------
>
>                 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
>         Environment: Oracle JDK 8
> Ubuntu Precise
>            Reporter: Tim Carey-Smith
>              Labels: compaction
>
> 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



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)