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https://issues.apache.org/jira/browse/MAPREDUCE-6063?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chris Douglas updated MAPREDUCE-6063:
-------------------------------------
Resolution: Fixed
Fix Version/s: 2.6.0
3.0.0
Hadoop Flags: Reviewed
Status: Resolved (was: Patch Available)
+1 Good catch
I committed this to trunk and branch-2
> In sortAndSpill of MapTask.java, size is calculated wrongly when bufend <
> bufstart.
> -----------------------------------------------------------------------------------
>
> Key: MAPREDUCE-6063
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6063
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mrv1, mrv2
> Reporter: zhihai xu
> Assignee: zhihai xu
> Fix For: 3.0.0, 2.6.0
>
> Attachments: MAPREDUCE-6063.000.patch
>
>
> In sortAndSpill of MapTask.java, size is calculated wrongly when bufend <
> bufstart. we should change (bufvoid - bufend) + bufstart to (bufvoid -
> bufstart) + bufend.
> Should change
> {code}
> long size = (bufend >= bufstart
> ? bufend - bufstart
> : (bufvoid - bufend) + bufstart) +
> partitions * APPROX_HEADER_LENGTH;
> {code}
> to:
> {code}
> long size = (bufend >= bufstart
> ? bufend - bufstart
> : (bufvoid - bufstart) + bufend) +
> partitions * APPROX_HEADER_LENGTH;
> {code}
> It is because when wraparound happen (bufend < bufstart) , the size should
> bufvoid - bufstart (bigger one) + bufend(small one).
> You can find similar code implementation in MapTask.java:
> {code}
> mapOutputByteCounter.increment(valend >= keystart
> ? valend - keystart
> : (bufvoid - keystart) + valend);
> {code}
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