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From "Michael Kjellman (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-9754) Make index info heap friendly for large CQL partitions
Date Fri, 11 Nov 2016 21:21:00 GMT


Michael Kjellman commented on CASSANDRA-9754:

[~llambiel] Yes, we ran out of disk space before the code fell over. We had some 250GB partitions
when we finally ran out of disk space. Waiting on review and comments from [~barnie] and I'm
working on the trunk version. I have most of the unit tests passing althuogh the new RangeTombstoneBounds
etc is proving pretty fragile and giving me a bit of pain.

[~jjirsa] as we've discussed i'm 99.9% sure we should go with your changes too.

> Make index info heap friendly for large CQL partitions
> ------------------------------------------------------
>                 Key: CASSANDRA-9754
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: sankalp kohli
>            Assignee: Michael Kjellman
>            Priority: Minor
>             Fix For: 4.x
>         Attachments: 0f8e28c220fd5af6c7b5dd2d3dab6936c4aa4b6b.patch, 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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