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https://issues.apache.org/jira/browse/HADOOP-10778?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14053937#comment-14053937
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Todd Lipcon commented on HADOOP-10778:
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BTW, I had suggested dynamically switching between java and native CRC32 about
5 years back, but Owen said he'd veto that:
https://issues.apache.org/jira/browse/HADOOP-6148?focusedCommentId=12721804&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-12721804
Perhaps he's changed his mind since then :)
The original JIRA also noted that OpenJDK was faster than Oracle's JDK at the
time. So perhaps that's the difference you're seeing between java 7 and java 6?
Are you testing OpenJDK in both cases or is it Oracle JDK 6?
> Use NativeCrc32 only if it is faster
> ------------------------------------
>
> Key: HADOOP-10778
> URL: https://issues.apache.org/jira/browse/HADOOP-10778
> Project: Hadoop Common
> Issue Type: Improvement
> Components: util
> Reporter: Tsz Wo Nicholas Sze
> Assignee: Tsz Wo Nicholas Sze
> Attachments: c10778_20140702.patch
>
>
> From the benchmark post in [this
> comment|https://issues.apache.org/jira/browse/HDFS-6560?focusedCommentId=14044060&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14044060],
> NativeCrc32 is slower than java.util.zip.CRC32 for Java 7 and above when
> bytesPerChecksum > 512.
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