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https://issues.apache.org/jira/browse/HADOOP-7401?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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monica beckwith updated HADOOP-7401:
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Status: Open (was: Patch Available)
> Unit test TestPureJavaCRC32 warmup code warms up the not-so-important loop in
> PureJavaCRC32.update()
> ----------------------------------------------------------------------------------------------------
>
> Key: HADOOP-7401
> URL: https://issues.apache.org/jira/browse/HADOOP-7401
> Project: Hadoop Common
> Issue Type: Improvement
> Components: test
> Affects Versions: 0.21.0
> Environment: Solaris-Sparcv9; Solaris-AMD64
> Reporter: monica beckwith
> Assignee: monica beckwith
> Priority: Minor
> Fix For: 0.21.0
>
> Attachments: hadoop-7401.patch
>
> Original Estimate: 1m
> Remaining Estimate: 1m
>
> When the warmup code sequence in TestPureJavaCRC32.java is executed, it sends
> size=len=2 and due to the value of 'trials' in for loop in doBench(), the
> crc.update() gets run > the compile threshold, thus providing the information
> that 'while 0<len<7' is a hot loop and 'while len>7' is a cold loop. This
> brings the MB/s number for len > 7 in PureJavaCRC32.update() way down (e.g.
> ~28.5% for size=len=65536).
> The workaround would be to use size=len=>7 (so just having size=len=2101
> ahead of size=len=2 will do the trick) in the warmup section.
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