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Robert Stupp commented on CASSANDRA-7438: ----------------------------------------- rehashing: growing (x2) is already implemented, shrinking (/2) shouldn't be a big issue, too. The implementation only locks the currently processed partitions during rehash. "put" operation: fixed (was definitely a bug), cleanup is running concurrently and trigger on "out of memory" condition block sizes: will give it a try (fixed vs. different sizes vs. variable sized (no blocks)) per-partition locks: already thought about it - not sure whether it's worth the additional RW-lock overhead since partition lock time is very low during normal operation metrics: some (very basic) metrics are already in it - will add some more timer metrics (configurable) [~vijay2...@yahoo.com] can you catch {{OutOfMemoryError}} for Unsafe.allocate() ? It should not go up the whole call stack. > 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. -- This message was sent by Atlassian JIRA (v6.3.4#6332)