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Robert Stupp commented on CASSANDRA-7438: ----------------------------------------- Just pushed some OHC additions to github: * key-iterator (used by CacheService class to invalidate column families) * (de)serialization of cache content to disk using direct I/O from off-heap. Means that the row cache content does not need to go though the heap for serialization and deserialization. Compression should also be possible in off-heap using the static methods in Snappy class since these expect direct buffers so there's nearly no pressure for that on the heap. Background: the implementation basically "lies" the address and length of the hash entry into DirectByteBuffer class so FileChannel is able to read into it/write from it. > 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, tests.zip > > > 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)