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https://issues.apache.org/jira/browse/YARN-3655?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14546508#comment-14546508
 ] 

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:blue}0{color} | pre-patch |  14m 39s | Pre-patch trunk compilation is 
healthy. |
| {color:green}+1{color} | @author |   0m  0s | The patch does not contain any 
@author tags. |
| {color:red}-1{color} | tests included |   0m  0s | The patch doesn't appear 
to include any new or modified tests.  Please justify why no new tests are 
needed for this patch. Also please list what manual steps were performed to 
verify this patch. |
| {color:green}+1{color} | javac |   7m 35s | There were no new javac warning 
messages. |
| {color:green}+1{color} | javadoc |   9m 31s | 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:green}+1{color} | checkstyle |   0m 53s | There were no new checkstyle 
issues. |
| {color:green}+1{color} | whitespace |   0m  0s | The patch has no lines that 
end in whitespace. |
| {color:green}+1{color} | install |   1m 35s | mvn install still works. |
| {color:green}+1{color} | eclipse:eclipse |   0m 33s | The patch built with 
eclipse:eclipse. |
| {color:red}-1{color} | findbugs |   1m 19s | The patch appears to introduce 1 
new Findbugs (version 2.0.3) warnings. |
| {color:red}-1{color} | yarn tests |  60m 16s | Tests failed in 
hadoop-yarn-server-resourcemanager. |
| | |  96m 47s | |
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|| Reason || Tests ||
| FindBugs | module:hadoop-yarn-server-resourcemanager |
|  |  Inconsistent synchronization of 
org.apache.hadoop.yarn.server.resourcemanager.recovery.FileSystemRMStateStore.isHDFS;
 locked 66% of time  Unsynchronized access at FileSystemRMStateStore.java:66% 
of time  Unsynchronized access at FileSystemRMStateStore.java:[line 156] |
| Timed out tests | 
org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.TestNodeLabelContainerAllocation
 |
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|| Subsystem || Report/Notes ||
| Patch URL | 
http://issues.apache.org/jira/secure/attachment/12733282/YARN-3655.000.patch |
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / 8f37873 |
| Findbugs warnings | 
https://builds.apache.org/job/PreCommit-YARN-Build/7956/artifact/patchprocess/newPatchFindbugsWarningshadoop-yarn-server-resourcemanager.html
 |
| hadoop-yarn-server-resourcemanager test log | 
https://builds.apache.org/job/PreCommit-YARN-Build/7956/artifact/patchprocess/testrun_hadoop-yarn-server-resourcemanager.txt
 |
| Test Results | 
https://builds.apache.org/job/PreCommit-YARN-Build/7956/testReport/ |
| Java | 1.7.0_55 |
| uname | Linux asf901.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/7956/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
>
>
> 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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