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https://issues.apache.org/jira/browse/CASSANDRA-7438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14222295#comment-14222295
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Vijay commented on CASSANDRA-7438:
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Alright the first version of pure Java version of LRUCache pushed,
* Basically a port from the C version. (Most of the test cases pass and they
are the same for both versions)
* As ariel mentioned before we can use disruptor for the ring buffer but this
doesn't use it yet.
* Expiry in the queue thread is not implemented yet.
* Algorithm to start the rehash needs to be more configurable and based on the
capacity will be pushing that soon.
* Overhead in JVM heap is just the segments array.
https://github.com/Vijay2win/lruc/tree/master/src/main/java/com/lruc/unsafe
> 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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