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From "Scott Carey (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-5598) Implement a pure Java CRC32 calculator
Date Thu, 18 Jun 2009 19:50:07 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-5598?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12721433#action_12721433
] 

Scott Carey commented on HADOOP-5598:
-------------------------------------

I additionally added my modifications to the test class and performance test to this JIRA.

> Implement a pure Java CRC32 calculator
> --------------------------------------
>
>                 Key: HADOOP-5598
>                 URL: https://issues.apache.org/jira/browse/HADOOP-5598
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: dfs
>            Reporter: Owen O'Malley
>            Assignee: Todd Lipcon
>         Attachments: crc32-results.txt, hadoop-5598-evil.txt, hadoop-5598-hybrid.txt,
hadoop-5598.txt, hadoop-5598.txt, PureJavaCrc32.java, PureJavaCrc32.java, PureJavaCrc32.java,
TestCrc32Performance.java, TestCrc32Performance.java, TestCrc32Performance.java, TestPureJavaCrc32.java
>
>
> We've seen a reducer writing 200MB to HDFS with replication = 1 spending a long time
in crc calculation. In particular, it was spending 5 seconds in crc calculation out of a total
of 6 for the write. I suspect that it is the java-jni border that is causing us grief.

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