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dhruba borthakur commented on HDFS-297:
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> During testing I ran on many more iterations than just the 24. W
Thanks for the info.
> I think we now have the fastest crc32 in the wes
Way to go!
> Implement a pure Java CRC32 calculator
> --------------------------------------
>
> Key: HDFS-297
> URL: https://issues.apache.org/jira/browse/HDFS-297
> Project: Hadoop HDFS
> Issue Type: Improvement
> 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, hdfs-297.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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