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From "Benedict (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-9738) Migrate key-cache to be fully off-heap
Date Tue, 08 Sep 2015 18:29:46 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-9738?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14735342#comment-14735342
] 

Benedict commented on CASSANDRA-9738:
-------------------------------------

It can actually be faster to compare the exact class instance, as this is pretty well optimised
by hotspot (and should just involve comparing the object headers). It is unlikely to make
_much_ of a difference here, especially with the shallow class hierarchy here, just noting
it.

In this case it looks like for correctness in the {{RowIndexEntry}} class it needs to be an
exact match anyway though.

The IndexedEntry doesn't need to duplicate those checks though, since they're performed by
the call to RIE.equals

> 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: 3.0.0 rc1
>
>
> 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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