[jira] [Updated] (CASSANDRA-3623) use MMapedBuffer in CompressedSegmentedFile.getSegment

["Jonathan Ellis (Updated) (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-3623?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis updated CASSANDRA-3623:
--------------------------------------

    Reviewer: yukim  (was: xedin)

I'll ask Yuki to take a look.
                
> use MMapedBuffer in CompressedSegmentedFile.getSegment
> ------------------------------------------------------
>
>                 Key: CASSANDRA-3623
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3623
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 1.1
>            Reporter: Vijay
>            Assignee: Vijay
>              Labels: compression
>             Fix For: 1.1
>
>         Attachments: 0001-MMaped-Compression-segmented-file-v2.patch, 0001-MMaped-Compression-segmented-file-v3.patch, 0001-MMaped-Compression-segmented-file.patch, 0002-tests-for-MMaped-Compression-segmented-file-v2.patch, 0002-tests-for-MMaped-Compression-segmented-file-v3.patch, CRC+MMapIO.xlsx, MMappedIO-Performance.docx
>
>
> CompressedSegmentedFile.getSegment seem to open a new file and doesnt seem to use the MMap and hence a higher CPU on the nodes and higher latencies on reads. 
> This ticket is to implement the TODO mentioned in CompressedRandomAccessReader
> // TODO refactor this to separate concept of "buffer to avoid lots of read() syscalls" and "compression buffer"
> but i think a separate class for the Buffer will be better.

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