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https://issues.apache.org/jira/browse/HADOOP-2247?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12553941
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Hadoop QA commented on HADOOP-2247:
-----------------------------------

+1 overall.  Here are the results of testing the latest attachment 
http://issues.apache.org/jira/secure/attachment/12372075/HADOOP-2220.patch
against trunk revision r606058.

    @author +1.  The patch does not contain any @author tags.

    javadoc +1.  The javadoc tool did not generate any warning messages.

    javac +1.  The applied patch does not generate any new compiler warnings.

    findbugs +1.  The patch does not introduce any new Findbugs warnings.

    core tests +1.  The patch passed core unit tests.

    contrib tests +1.  The patch passed contrib unit tests.

Test results: 
http://lucene.zones.apache.org:8080/hudson/job/Hadoop-Patch/1417/testReport/
Findbugs warnings: 
http://lucene.zones.apache.org:8080/hudson/job/Hadoop-Patch/1417/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: 
http://lucene.zones.apache.org:8080/hudson/job/Hadoop-Patch/1417/artifact/trunk/build/test/checkstyle-errors.html
Console output: 
http://lucene.zones.apache.org:8080/hudson/job/Hadoop-Patch/1417/console

This message is automatically generated.

> Mappers fail easily due to repeated failures
> --------------------------------------------
>
>                 Key: HADOOP-2247
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2247
>             Project: Hadoop
>          Issue Type: Bug
>    Affects Versions: 0.15.0
>         Environment: 1400 Node hadoop cluster
>            Reporter: Srikanth Kakani
>            Assignee: Amar Kamat
>            Priority: Blocker
>             Fix For: 0.15.2
>
>         Attachments: HADOOP-2220.patch, HADOOP-2220.patch, HADOOP-2220.patch
>
>
> Related to HADOOP-2220, problem introduced in HADOOP-1158
> At this scale hardcoding the number of fetch failures to a static number: in 
> this case 3 is never going to work. Although the jobs we are running are 
> loading the systems 3 failures can randomly occur within the lifetime of a 
> map. Even fetching the data can cause enough load for so many failures to 
> occur.
> We believe that number of tasks and size of cluster should be taken into 
> account. Based on which we believe that a ratio between total fetch attempts 
> and total failed attempts should be taken into consideration.
> Given our experience with a task should be declared "Too many fetch failures" 
> based on:
> failures > n /*could be 3*/ && (failures/total attempts) > k% /*could be 
> 30-40%*/
> Basically the first factor is to give some headstart to the second factor, 
> second factor then takes into account the cluster size and the task size.
> Additionally we could take recency into account, say failures and attempts in 
> last one hour. We do not want to make it too small.

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