T Jake Luciani created CASSANDRA-8464:
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Summary: Support direct buffer decompression for reads
Key: CASSANDRA-8464
URL: https://issues.apache.org/jira/browse/CASSANDRA-8464
Project: Cassandra
Issue Type: Improvement
Reporter: T Jake Luciani
Assignee: T Jake Luciani
Fix For: 3.0
Currently when we read a compressed sstable we copy the data on heap then send
it to be de-compressed to another on heap buffer (albeit pooled).
But now both snappy and lz4 (with CASSANDRA-7039) allow decompression of direct
byte buffers. This lets us mmap the data and decompress completely off heap
(and avoids moving bytes over JNI).
One issue is performing the checksum offheap but the Adler32 does support in
java 8 (it's also in java 7 but marked private?!)
This change yields a > 10% boost in read performance on cstar. Locally I see
upto 30% improvement.
http://cstar.datastax.com/graph?stats=5ebcdd70-816b-11e4-aed6-42010af0688f&metric=op_rate&operation=2_read&smoothing=1&show_aggregates=true&xmin=0&xmax=200.09&ymin=0&ymax=135908.3
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