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Date: Thu, 22 Dec 2011 21:03:30 +0000 (UTC)
From: "Jonathan Ellis (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (CASSANDRA-3610) Checksum improvement for
 CompressedRandomAccessReader
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    [ https://issues.apache.org/jira/browse/CASSANDRA-3610?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13175059#comment-13175059 ] 

Jonathan Ellis commented on CASSANDRA-3610:
-------------------------------------------

So... Sun JDK JNI is 2x as fast as OpenJDK, is that the takeaway?
                
> Checksum improvement for CompressedRandomAccessReader
> -----------------------------------------------------
>
>                 Key: CASSANDRA-3610
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3610
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 1.1
>         Environment: JVM
>            Reporter: Vijay
>            Assignee: Vijay
>            Priority: Minor
>             Fix For: 1.1
>
>         Attachments: 0001-use-pure-java-CRC32-v2.patch, 0001-use-pure-java-CRC32.patch, TestCrc32Performance.java
>
>
> When compression is on, Currently we see checksum taking up about 40% of the CPU more than snappy library.
> Looks like hadoop solved it by implementing their own checksum, we can either use it or implement something like that.
> http://images.slidesharecdn.com/1toddlipconyanpeichen-cloudera-hadoopandperformance-final-111110132228-phpapp01-slide-15-768.jpg?1321043717
> in our test env it provided 50% improvement over native implementation which uses jni to call the OS.

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