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https://issues.apache.org/jira/browse/YARN-3655?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14575924#comment-14575924
 ] 

Hadoop QA commented on YARN-3655:
---------------------------------

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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:red}-1{color} | pre-patch |  15m  2s | Findbugs (version ) appears to 
be broken on trunk. |
| {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 35s | There were no new javac warning 
messages. |
| {color:green}+1{color} | javadoc |   9m 36s | There were no new javadoc 
warning messages. |
| {color:green}+1{color} | release audit |   0m 22s | The applied patch does 
not increase the total number of release audit warnings. |
| {color:green}+1{color} | checkstyle |   0m 23s | There were no new checkstyle 
issues. |
| {color:green}+1{color} | whitespace |   0m  4s | The patch has no lines that 
end in whitespace. |
| {color:green}+1{color} | install |   1m 34s | mvn install still works. |
| {color:green}+1{color} | eclipse:eclipse |   0m 33s | The patch built with 
eclipse:eclipse. |
| {color:green}+1{color} | findbugs |   1m 26s | The patch does not introduce 
any new Findbugs (version 3.0.0) warnings. |
| {color:red}-1{color} | yarn tests |  50m 17s | Tests failed in 
hadoop-yarn-server-resourcemanager. |
| | |  86m 55s | |
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|| Reason || Tests ||
| Failed unit tests | 
hadoop.yarn.server.resourcemanager.TestWorkPreservingRMRestart |
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|| Subsystem || Report/Notes ||
| Patch URL | 
http://issues.apache.org/jira/secure/attachment/12738190/YARN-3655.004.patch |
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / 71de367 |
| hadoop-yarn-server-resourcemanager test log | 
https://builds.apache.org/job/PreCommit-YARN-Build/8208/artifact/patchprocess/testrun_hadoop-yarn-server-resourcemanager.txt
 |
| Test Results | 
https://builds.apache.org/job/PreCommit-YARN-Build/8208/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/8208/console |


This message was automatically generated.

> FairScheduler: potential livelock due to maxAMShare limitation and container 
> reservation 
> -----------------------------------------------------------------------------------------
>
>                 Key: YARN-3655
>                 URL: https://issues.apache.org/jira/browse/YARN-3655
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: fairscheduler
>    Affects Versions: 2.7.0
>            Reporter: zhihai xu
>            Assignee: zhihai xu
>         Attachments: YARN-3655.000.patch, YARN-3655.001.patch, 
> YARN-3655.002.patch, YARN-3655.003.patch, YARN-3655.004.patch
>
>
> FairScheduler: potential livelock due to maxAMShare limitation and container 
> reservation.
> If a node is reserved by an application, all the other applications don't 
> have any chance to assign a new container on this node, unless the 
> application which reserves the node assigns a new container on this node or 
> releases the reserved container on this node.
> The problem is if an application tries to call assignReservedContainer and 
> fail to get a new container due to maxAMShare limitation, it will block all 
> other applications to use the nodes it reserves. If all other running 
> applications can't release their AM containers due to being blocked by these 
> reserved containers. A livelock situation can happen.
> The following is the code at FSAppAttempt#assignContainer which can cause 
> this potential livelock.
> {code}
>     // Check the AM resource usage for the leaf queue
>     if (!isAmRunning() && !getUnmanagedAM()) {
>       List<ResourceRequest> ask = appSchedulingInfo.getAllResourceRequests();
>       if (ask.isEmpty() || !getQueue().canRunAppAM(
>           ask.get(0).getCapability())) {
>         if (LOG.isDebugEnabled()) {
>           LOG.debug("Skipping allocation because maxAMShare limit would " +
>               "be exceeded");
>         }
>         return Resources.none();
>       }
>     }
> {code}
> To fix this issue, we can unreserve the node if we can't allocate the AM 
> container on the node due to Max AM share limitation and the node is reserved 
> by the application.



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