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From "T Jake Luciani (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-8464) Support direct buffer decompression for reads
Date Tue, 24 Nov 2015 14:24:11 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-8464?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

T Jake Luciani updated CASSANDRA-8464:
--------------------------------------
    Component/s: Local Write-Read Paths

> Support direct buffer decompression for reads
> ---------------------------------------------
>
>                 Key: CASSANDRA-8464
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8464
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Local Write-Read Paths
>            Reporter: T Jake Luciani
>            Assignee: T Jake Luciani
>              Labels: performance
>             Fix For: 2.2.0 beta 1
>
>         Attachments: compression_direct.png
>
>
> 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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