[jira] [Commented] (KAFKA-2303) Fix for KAFKA-2235 LogCleaner offset map overflow causes another compaction failures

["Jiangjie Qin (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-2303?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14622767#comment-14622767 ] 

Jiangjie Qin commented on KAFKA-2303:
-------------------------------------

Would the following help solve the issue?
1. Make log.cleaner.min.cleanable.ratio to be smaller
2. Make log.cleaner.backoff.ms smaller
It is supposedly make each cleaning scan over less records but do the cleaning more frequently. That should help a little bit.

> Fix for KAFKA-2235 LogCleaner offset map overflow causes another compaction failures
> ------------------------------------------------------------------------------------
>
>                 Key: KAFKA-2303
>                 URL: https://issues.apache.org/jira/browse/KAFKA-2303
>             Project: Kafka
>          Issue Type: Bug
>          Components: core, log
>    Affects Versions: 0.8.2.1
>            Reporter: Alexander Demidko
>            Assignee: Jay Kreps
>             Fix For: 0.8.3
>
>
> We have rolled out the patch for KAFKA-2235 to our kafka cluster, and recently instead of 
> {code}
> "kafka.log.LogCleaner - [kafka-log-cleaner-thread-0], Error due to
> java.lang.IllegalArgumentException: requirement failed: Attempt to add a new entry to a full offset map." 
> {code}
> we started to see 
> {code}
> kafka.log.LogCleaner - [kafka-log-cleaner-thread-0], Error due to
> java.lang.IllegalArgumentException: requirement failed: 131390902 messages in segment <topic-name>-cgstate-8/00000000000079840768.log but offset map can fit only 80530612. You can increase log.cleaner.dedupe.buffer.size or decrease log.cleaner.threads
> {code}
> So, we had to roll it back to avoid disk depletion although I'm not sure if it needs to be rolled back in trunk. This patch applies more strict checks than were in place before: even if there is only one unique key for a segment, cleanup will fail if this segment is too big. 
> Does it make sense to eliminate a limit for the offset map slots count, for example to use an offset map backed by a memory mapped file?
> The limit of 80530612 slots comes from memory / bytesPerEntry, where memory is Int.MaxValue (we use only one cleaner thread) and bytesPerEntry is 8 + digest hash size. Might be wrong, but it seems if the overall number of unique keys per partition is more than 80M slots in an OffsetMap, compaction will always fail and cleaner thread will die. 



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