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https://issues.apache.org/jira/browse/MAPREDUCE-2324?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Robert Joseph Evans updated MAPREDUCE-2324:
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Attachment: MR-2324-security-v2.txt
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[exec] +1 overall.
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[exec] +1 @author. The patch does not contain any @author tags.
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[exec] +1 tests included. The patch appears to include 6 new or
modified tests.
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[exec] +1 javadoc. The javadoc tool did not generate any warning
messages.
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[exec] +1 javac. The applied patch does not increase the total number
of javac compiler warnings.
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[exec] +1 findbugs. The patch does not introduce any new Findbugs
(version 1.3.9) warnings.
I also did some math. On our largest cluster here at Yahoo! we have < 5000
machines and at most about 200 jobs running concurrently. That comes out to
about 8-16 MB in extra heap usage on the JT, if the HashMap is half full and
all of those 200 jobs are about to fail because of reduce scheduling issues.
> Job should fail if a reduce task can't be scheduled anywhere
> ------------------------------------------------------------
>
> Key: MAPREDUCE-2324
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2324
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 0.20.2, 0.20.205.0
> Reporter: Todd Lipcon
> Assignee: Robert Joseph Evans
> Attachments: MR-2324-security-v1.txt, MR-2324-security-v2.txt
>
>
> If there's a reduce task that needs more disk space than is available on any
> mapred.local.dir in the cluster, that task will stay pending forever. For
> example, we produced this in a QA cluster by accidentally running terasort
> with one reducer - since no mapred.local.dir had 1T free, the job remained in
> pending state for several days. The reason for the "stuck" task wasn't clear
> from a user perspective until we looked at the JT logs.
> Probably better to just fail the job if a reduce task goes through all TTs
> and finds that there isn't enough space.
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