[KAFKA-6828] Index files are no longer sparse in Java 9/10 due to OpenJDK regression

• Type: Improvement
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.0.0
• Component/s: core
• Environment: CentosOS 7 on EXT4 FS
• Assignee: Unassigned
• Reporter: Enrico Olivelli
• Created: 26/Apr/18 11:09
• Updated: 10/May/18 14:05
• Resolved: 10/May/18 14:05

Description

This is a very strage case. I have a Kafka broker (part of a cluster of 3 brokers) which cannot start upgrading Java from Oracle JDK8 to Oracle JDK 9.0.4 (the same with JDK 10.0.0)

There are a lot of .index and .timeindex files taking 10MB, they are for empty partiions.

Running with Java 9 the server seems to rebuild these files and each file takes "really" 10MB.The sum of all the files (calculated using du -sh) is 22GB and the broker crashes during startup, disk becomes full and no log more is written. (I can send an extraction of the logs, but the tell only  about 'rebuilding index', the same as on Java 8)

Reverting the same broker to Java 8 and removing the index files, the broker rebuilds such files, each files take 10MB, but the full sum of sizes (calculated using du -sh) is 38 MB !

I am running this broker on CentosOS 7 on EXT4 FS.

I have upgraded the broker to latest and greatest Kafka 1.0.0 (from 0.10.2) without any success.
 
After checking on JDK nio-dev list it appears a regresion in the behaviour of RandomAccessFile
 Just for reference see this discussion  on nio-dev list on OpenJDK
http://mail.openjdk.java.net/pipermail/nio-dev/2018-April/005008.html

see
https://bugs.openjdk.java.net/browse/JDK-8168628