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https://issues.apache.org/jira/browse/CASSANDRA-3623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13176126#comment-13176126
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Pavel Yaskevich commented on CASSANDRA-3623:
--------------------------------------------
CASSANDRA-3610 needs rebase to be applied on the latest trunk. Also I took a
look at the doc you have attached and it looks like test for 10000 is broken
because stress command line shows that you use -S 3000 instead of 10000.
{noformat}
Compressed Reads: *10,000* columnSize:
[vijay_tcasstest@vijay_tcass--1a-i-2801d94a ~]$ java -Xms2G -Xmx2G -Xmn1G
-XX:+HeapDumpOnOutOfMemoryError -Xss128k -XX:+UseParNewGC
-XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:SurvivorRatio=8
-XX:MaxTenuringThreshold=1 -XX:CMSInitiatingOccupancyFraction=75
-XX:+UseCMSInitiatingOccupancyOnly -jar Stress.jar -p 7102 -d 10.87.81.75 -n
500000 -S *3000* -I SnappyCompressor -o read
{noformat}
Also as I mentioned before - you test on the different nodes on the working
cluster, there are side factors that could be affecting test results. Can you
please explain why testing performance on the working cluster is a good idea?
> 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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