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https://issues.apache.org/jira/browse/CASSANDRA-7438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14227250#comment-14227250
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Jonathan Ellis commented on CASSANDRA-7438:
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Looking at the discussion, I wonder if we're overcomplicating things. I think
it got a bit lost in the noise when Ariel said earlier,
bq. I also wonder if splitting the cache into several instances each with a
coarse lock per instance wouldn't result in simpler, fast-enough code. I don't
want to advocate doing something different for performance, but rather that
there is the possibility of a relatively simple implementation via Unsafe.
Why not start with something like that and see if it's Good Enough? I suspect
that at that point other bottlenecks will be much more important, so paying a
high complexity cost to optimize the cache further would be a bad trade overall.
> 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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