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Posted to mapreduce-issues@hadoop.apache.org by "zhihai xu (JIRA)" <ji...@apache.org> on 2014/09/02 21:38:21 UTC
[jira] [Updated] (MAPREDUCE-6063) In sortAndSpill of MapTask.java,
size is calculated wrongly when bufend < bufstart.
[ https://issues.apache.org/jira/browse/MAPREDUCE-6063?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
zhihai xu updated MAPREDUCE-6063:
---------------------------------
Attachment: MAPREDUCE-6063.000.patch
> 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
> 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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