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https://issues.apache.org/jira/browse/HADOOP-3961?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12664038#action_12664038
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Xing Shi commented on HADOOP-3961:
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Hi, I have meet a special resource estimateion work. Several of the map's input
files is zero, but there is also several bytes created in map's output. So :
double blowupOnThisTask = ts.getOutputSize() /
((double) tip.getMapInputSize() + 1);
blowupOnThisTask will be increased large, and the reduces can't be allocated
the reduce tasks from the JobTracker.
> resource estimation works badly in some cases
> ---------------------------------------------
>
> Key: HADOOP-3961
> URL: https://issues.apache.org/jira/browse/HADOOP-3961
> Project: Hadoop Core
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.19.0
> Reporter: Ari Rabkin
> Assignee: Ari Rabkin
> Priority: Blocker
> Fix For: 0.19.0
>
> Attachments: resourceEstFix.patch
>
>
> The disk space estimation introduced in HADOOP-657 performs badly under some
> circumstances. In particular, if maps have very small output, the initial
> estimate of output size equals input size throws everything off.
> Fix is to use a smaller initial estimate, and to update it appropriately.
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