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Posted to mapreduce-issues@hadoop.apache.org by "Karthik Kambatla (JIRA)" <ji...@apache.org> on 2013/06/03 00:52:20 UTC
[jira] [Assigned] (MAPREDUCE-5288)
ResourceEstimator#getEstimatedTotalMapOutputSize suffers from divide by
zero issues
[ https://issues.apache.org/jira/browse/MAPREDUCE-5288?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Karthik Kambatla reassigned MAPREDUCE-5288:
-------------------------------------------
Assignee: Karthik Kambatla
> ResourceEstimator#getEstimatedTotalMapOutputSize suffers from divide by zero issues
> -----------------------------------------------------------------------------------
>
> Key: MAPREDUCE-5288
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5288
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mrv1
> Affects Versions: 1.2.0
> Reporter: Harsh J
> Assignee: Karthik Kambatla
>
> The computation in the above mentioned class-method is below:
> {code}
> long estimate = Math.round(((double)inputSize *
> completedMapsOutputSize * 2.0)/completedMapsInputSize);
> {code}
> Given http://docs.oracle.com/javase/6/docs/api/java/lang/Math.html#round(double), its possible that the returned estimate could be Long.MAX_VALUE if completedMapsInputSize is determined to be zero.
> This can be proven with a simple code snippet:
> {code}
> class Foo {
> public static void main(String... args) {
> long inputSize = 600L + 2;
> long estimate = Math.round(((double)inputSize *
> 1L * 2.0)/0L);
> System.out.println(estimate);
> }
> }
> {code}
> The above conveniently prints out: {{9223372036854775807}}, which is Long.MAX_VALUE (or 8 Exbibytes per MapReduce).
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