[jira] [Commented] (CASSANDRA-14239) OutOfMemoryError when bootstrapping with less than 100GB RAM

["Kurt Greaves (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-14239?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16370967#comment-16370967 ] 

Kurt Greaves commented on CASSANDRA-14239:
------------------------------------------

Don't know that people have had great success with G1. Seems like the memtables are using up too much memory but anyway you should try with a smaller heap and/or CMS. Maybe try offheap memtables as well? Seems like there might still be a bug here though.

> OutOfMemoryError when bootstrapping with less than 100GB RAM
> ------------------------------------------------------------
>
>                 Key: CASSANDRA-14239
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14239
>             Project: Cassandra
>          Issue Type: Bug
>         Environment: Details of the bootstrapping Node
>  * ProLiant BL460c G7
>  * 56GB RAM
>  * 2x 146GB 10K HDD (One dedicated for Commitlog, one for Data, Hints and saved_caches)
>  * CentOS 7.4 on SD-Card
>  * /tmp and /var/log on tmpfs
>  * Oracle JDK 1.8.0_151
>  * Cassandra 3.11.1
> Cluster
>  * 10 existing Nodes (Up and Normal)
>            Reporter: Jürgen Albersdorfer
>            Priority: Major
>         Attachments: Objects-by-class.csv, Objects-with-biggest-retained-size.csv, cassandra-env.sh, cassandra.yaml, jvm.options, jvm_opts.txt, stack-traces.txt
>
>
> Hi, I face an issue when bootstrapping a Node having less than 100GB RAM on our 10 Node C* 3.11.1 Cluster.
> During bootstrap, when I watch the cassandra.log I observe a growth in JVM Heap Old Gen which gets not significantly freed up any more.
> I know that JVM collects on Old Gen only when really needed. I can see collections, but there is always a remainder which seems to grow forever without ever getting freed.
> After the Node successfully Joined the Cluster, I can remove the extra RAM I have given it for bootstrapping without any further effect.
> It feels like Cassandra will not forget about every single byte streamed over the Network over time during bootstrapping, - which would be a memory leak and a major problem, too.
> I was able to produce a HeapDumpOnOutOfMemoryError from a 56GB Node (40 GB assigned JVM Heap). YourKit Profiler shows huge amount of Memory allocated for org.apache.cassandra.db.Memtable (22 GB) org.apache.cassandra.db.rows.BufferCell (19 GB) and java.nio.HeapByteBuffer (11 GB)



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