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https://issues.apache.org/jira/browse/HADOOP-11466?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Suman Somasundar updated HADOOP-11466:
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Status: In Progress (was: Patch Available)
> FastByteComparisons: do not use UNSAFE_COMPARER on the SPARC architecture
> because it is slower there
> ----------------------------------------------------------------------------------------------------
>
> Key: HADOOP-11466
> URL: https://issues.apache.org/jira/browse/HADOOP-11466
> Project: Hadoop Common
> Issue Type: Improvement
> Components: io, performance, util
> Environment: Linux X86 and Solaris SPARC
> Reporter: Suman Somasundar
> Assignee: Suman Somasundar
> Priority: Minor
> Labels: patch
> Attachments: HADOOP-11466.001.patch
>
>
> One difference between Hadoop 2.x and Hadoop 1.x is a utility to compare two
> byte arrays at coarser 8-byte granularity instead of at the byte-level. The
> discussion at HADOOP-7761 says this fast byte comparison is somewhat faster
> for longer arrays and somewhat slower for smaller arrays ( AVRO-939). In
> order to do 8-byte reads on addresses not aligned to 8-byte boundaries, the
> patch uses Unsafe.getLong. The problem is that this call is incredibly
> expensive on SPARC. The reason is that the Studio compiler detects an
> unaligned pointer read and handles this read in software. x86 supports
> unaligned reads, so there is no penalty for this call on x86.
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