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https://issues.apache.org/jira/browse/CASSANDRA-7438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14145338#comment-14145338
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Robert Stupp commented on CASSANDRA-7438:
-----------------------------------------
(note: [[email protected]], please use the other nick)
Some quick notes:
* Can you add the assertion for {{capacity <= 0}} to
{{OffheapCacheProvider.create}} - the current error message if
{{row_cache_size_in_mb}} is not set (or invalid) "capacity should be set" could
be more fleshy
* Additionally the {{capacity}} check should also check for negative values (it
starts with a negative value - don't know what happens if it is negative...)
* {{org.apache.cassandra.db.RowCacheTest#testRowCacheCleanup}} fails at the
last assertion - all other unit tests seem to work
* Documentation in cassandra.yaml for row_cache_provider could be a bit more
verbose - just some abstract about the characteristics and limitation (e.g.
Offheap does only work on Linux + OSX) of both implementations
* IMO it would be fine to have a general unit test for
{{com.lruc.api.LRUCache}} in C* code, too
* Please add an adopted copy of {{RowCacheTest}} for OffheapCacheProvider
* unit tests using OffheapCacheProvider must not start on Windows builds -
please add an assertion in OffHeapCacheProvider to assert that it runs on Linux
or OSX
Sorry for the late reply
> 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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