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https://issues.apache.org/jira/browse/CASSANDRA-7438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14193074#comment-14193074
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Robert Stupp commented on CASSANDRA-7438:
-----------------------------------------

bq. total 1 byte profit
bikeshed : could be two if serialized "unencoded" :)
I took some time to see whether it could be some lhf to change that - but it 
isn't really (because there are some uses of {{DataIn/Output(Plus)}} that would 
need to be changed, too - and it is used widely - even (if I saw that 
correctly) in SSTables (the point at which I stopped investigating ;) )

> Serializing Row cache alternative (Fully off heap)
> --------------------------------------------------
>
>                 Key: CASSANDRA-7438
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7438
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>         Environment: Linux
>            Reporter: Vijay
>            Assignee: Vijay
>              Labels: performance
>             Fix For: 3.0
>
>         Attachments: 0001-CASSANDRA-7438.patch
>
>
> Currently SerializingCache is partially off heap, keys are still stored in 
> JVM heap as BB, 
> * There is a higher GC costs for a reasonably big cache.
> * Some users have used the row cache efficiently in production for better 
> results, but this requires careful tunning.
> * Overhead in Memory for the cache entries are relatively high.
> So the proposal for this ticket is to move the LRU cache logic completely off 
> heap and use JNI to interact with cache. We might want to ensure that the new 
> implementation match the existing API's (ICache), and the implementation 
> needs to have safe memory access, low overhead in memory and less memcpy's 
> (As much as possible).
> We might also want to make this cache configurable.



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