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Date: Sun, 6 Sep 2015 22:07:46 +0000 (UTC)
From: "Hadoop QA (JIRA)" <jira@apache.org>
To: yarn-issues@hadoop.apache.org
Message-ID: <JIRA.12733524.1407858960000.269580.1441577266700@Atlassian.JIRA>
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 <JIRA.12733524.1407858960642@arcas>
Subject: [jira] [Commented] (YARN-2410) Nodemanager ShuffleHandler can
 possible exhaust file descriptors
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    [ https://issues.apache.org/jira/browse/YARN-2410?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14733149#comment-14733149 ] 

Hadoop QA commented on YARN-2410:
---------------------------------

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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | pre-patch |  15m 44s | Pre-patch trunk compilation is healthy. |
| {color:green}+1{color} | @author |   0m  0s | The patch does not contain any @author tags. |
| {color:green}+1{color} | tests included |   0m  0s | The patch appears to include 1 new or modified test files. |
| {color:green}+1{color} | javac |   7m 44s | There were no new javac warning messages. |
| {color:green}+1{color} | javadoc |   9m 51s | There were no new javadoc warning messages. |
| {color:green}+1{color} | release audit |   0m 23s | The applied patch does not increase the total number of release audit warnings. |
| {color:red}-1{color} | checkstyle |   0m 21s | The applied patch generated  14 new checkstyle issues (total was 60, now 74). |
| {color:red}-1{color} | whitespace |   0m  1s | The patch has 1  line(s) that end in whitespace. Use git apply --whitespace=fix. |
| {color:green}+1{color} | install |   1m 28s | mvn install still works. |
| {color:green}+1{color} | eclipse:eclipse |   0m 33s | The patch built with eclipse:eclipse. |
| {color:red}-1{color} | findbugs |   0m 47s | The patch appears to introduce 1 new Findbugs (version 3.0.0) warnings. |
| {color:green}+1{color} | mapreduce tests |   0m 21s | Tests passed in hadoop-mapreduce-client-shuffle. |
| | |  37m 15s | |
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|| Reason || Tests ||
| FindBugs | module:hadoop-mapreduce-client-shuffle |
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|| Subsystem || Report/Notes ||
| Patch URL | http://issues.apache.org/jira/secure/attachment/12754414/YARN-2410-v6.patch |
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / 9b68577 |
| checkstyle |  https://builds.apache.org/job/PreCommit-YARN-Build/9019/artifact/patchprocess/diffcheckstylehadoop-mapreduce-client-shuffle.txt |
| whitespace | https://builds.apache.org/job/PreCommit-YARN-Build/9019/artifact/patchprocess/whitespace.txt |
| Findbugs warnings | https://builds.apache.org/job/PreCommit-YARN-Build/9019/artifact/patchprocess/newPatchFindbugsWarningshadoop-mapreduce-client-shuffle.html |
| hadoop-mapreduce-client-shuffle test log | https://builds.apache.org/job/PreCommit-YARN-Build/9019/artifact/patchprocess/testrun_hadoop-mapreduce-client-shuffle.txt |
| Test Results | https://builds.apache.org/job/PreCommit-YARN-Build/9019/testReport/ |
| Java | 1.7.0_55 |
| uname | Linux asf905.gq1.ygridcore.net 3.13.0-36-lowlatency #63-Ubuntu SMP PREEMPT Wed Sep 3 21:56:12 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux |
| Console output | https://builds.apache.org/job/PreCommit-YARN-Build/9019/console |


This message was automatically generated.

> Nodemanager ShuffleHandler can possible exhaust file descriptors
> ----------------------------------------------------------------
>
>                 Key: YARN-2410
>                 URL: https://issues.apache.org/jira/browse/YARN-2410
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: nodemanager
>    Affects Versions: 2.5.0
>            Reporter: Nathan Roberts
>            Assignee: Kuhu Shukla
>         Attachments: YARN-2410-v1.patch, YARN-2410-v2.patch, YARN-2410-v3.patch, YARN-2410-v4.patch, YARN-2410-v5.patch, YARN-2410-v6.patch
>
>
> The async nature of the shufflehandler can cause it to open a huge number of
> file descriptors, when it runs out it crashes.
> Scenario:
> Job with 6K reduces, slow start set to 0.95, about 40 map outputs per node.
> Let's say all 6K reduces hit a node at about same time asking for their
> outputs. Each reducer will ask for all 40 map outputs over a single socket in a
> single request (not necessarily all 40 at once, but with coalescing it is
> likely to be a large number).
> sendMapOutput() will open the file for random reading and then perform an async transfer of the particular portion of this file(). This will theoretically
> happen 6000*40=240000 times which will run the NM out of file descriptors and cause it to crash.
> The algorithm should be refactored a little to not open the fds until they're
> actually needed. 


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