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From "Michael Kjellman (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-9754) Make index info heap friendly for large CQL partitions
Date Mon, 17 Oct 2016 20:10:58 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-9754?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15583305#comment-15583305
] 

Michael Kjellman commented on CASSANDRA-9754:
---------------------------------------------

Sure, I can change the test right now. Which table specifically are you talking about adding
more keys, it's a single command line parameter and a restart of the perf load? I'll need
to bounce the cluster for the key cache change obviously though.

The control cluster which had 2.1.16 without Birch which I did on purpose to see how performance
was with Birch vs without to specifically make sure there wasn't a regression at the low end
like you're rightfully concerned about (as I am/was too). 

> Make index info heap friendly for large CQL partitions
> ------------------------------------------------------
>
>                 Key: CASSANDRA-9754
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9754
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: sankalp kohli
>            Assignee: Michael Kjellman
>            Priority: Minor
>             Fix For: 4.x
>
>         Attachments: gc_collection_times_with_birch.png, gc_collection_times_without_birch.png,
gc_counts_with_birch.png, gc_counts_without_birch.png, perf_cluster_1_with_birch_read_latency_and_counts.png,
perf_cluster_1_with_birch_write_latency_and_counts.png, perf_cluster_2_with_birch_read_latency_and_counts.png,
perf_cluster_2_with_birch_write_latency_and_counts.png, perf_cluster_3_without_birch_read_latency_and_counts.png,
perf_cluster_3_without_birch_write_latency_and_counts.png
>
>
>  Looking at a heap dump of 2.0 cluster, I found that majority of the objects are IndexInfo
and its ByteBuffers. This is specially bad in endpoints with large CQL partitions. If a CQL
partition is say 6,4GB, it will have 100K IndexInfo objects and 200K ByteBuffers. This will
create a lot of churn for GC. Can this be improved by not creating so many objects?



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