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https://issues.apache.org/jira/browse/CASSANDRA-9738?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14719307#comment-14719307
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Ariel Weisberg commented on CASSANDRA-9738:
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For observers. We hit a snag. The key cache values can be quite large. There is
an entry in each value for every row per partition so it can be in the
thousands. This likely means that copying the entire thing on heap to operate
on it once per read is not going to match the performance of the existing POJO
implementation. Robert is going to benchmark a more representative
configuration.
It's a tractable problem but we will need to an off heap list implementation
for variable size objects that supports binary search without materializing
each entry in the search.
> Migrate key-cache to be fully off-heap
> --------------------------------------
>
> Key: CASSANDRA-9738
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9738
> Project: Cassandra
> Issue Type: Sub-task
> Reporter: Robert Stupp
> Assignee: Robert Stupp
> Fix For: 3.0 beta 2
>
>
> Key cache still uses a concurrent map on-heap. This could go to off-heap and
> feels doable now after CASSANDRA-8099.
> Evaluation should be done in advance based on a POC to prove that pure
> off-heap counter cache buys a performance and/or gc-pressure improvement.
> In theory, elimination of on-heap management of the map should buy us some
> benefit.
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