[jira] [Commented] (YARN-4095) Avoid sharing AllocatorPerContext object in LocalDirAllocator between ShuffleHandler and LocalDirsHandlerService.

["Hadoop QA (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-4095?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14900178#comment-14900178 ] 

Hadoop QA commented on YARN-4095:
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| (/) *{color:green}+1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | pre-patch |  16m 23s | 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 51s | There were no new javac warning messages. |
| {color:green}+1{color} | javadoc |  10m  2s | 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 36s | 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 28s | mvn install still works. |
| {color:green}+1{color} | eclipse:eclipse |   0m 33s | The patch built with eclipse:eclipse. |
| {color:green}+1{color} | findbugs |   1m 12s | The patch does not introduce any new Findbugs (version 3.0.0) warnings. |
| {color:green}+1{color} | yarn tests |   7m 49s | Tests passed in hadoop-yarn-server-nodemanager. |
| | |  46m 21s | |
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|| Subsystem || Report/Notes ||
| Patch URL | http://issues.apache.org/jira/secure/attachment/12761363/YARN-4095.001.patch |
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / 3a9c707 |
| hadoop-yarn-server-nodemanager test log | https://builds.apache.org/job/PreCommit-YARN-Build/9226/artifact/patchprocess/testrun_hadoop-yarn-server-nodemanager.txt |
| Test Results | https://builds.apache.org/job/PreCommit-YARN-Build/9226/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/9226/console |


This message was automatically generated.

> Avoid sharing AllocatorPerContext object in LocalDirAllocator between ShuffleHandler and LocalDirsHandlerService.
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: YARN-4095
>                 URL: https://issues.apache.org/jira/browse/YARN-4095
>             Project: Hadoop YARN
>          Issue Type: Improvement
>          Components: nodemanager
>            Reporter: zhihai xu
>            Assignee: zhihai xu
>         Attachments: YARN-4095.000.patch, YARN-4095.001.patch
>
>
> Currently {{ShuffleHandler}} and {{LocalDirsHandlerService}} share {{AllocatorPerContext}} object in {{LocalDirAllocator}} for configuration {{NM_LOCAL_DIRS}} because {{AllocatorPerContext}} are stored in a static TreeMap with configuration name as key
> {code}
>   private static Map <String, AllocatorPerContext> contexts = 
>                  new TreeMap<String, AllocatorPerContext>();
> {code}
> {{LocalDirsHandlerService}} and {{ShuffleHandler}} both create a {{LocalDirAllocator}} using {{NM_LOCAL_DIRS}}. Even they don't use the same {{Configuration}} object, but they will use the same {{AllocatorPerContext}} object. Also {{LocalDirsHandlerService}} may change {{NM_LOCAL_DIRS}} value in its {{Configuration}} object to exclude full and bad local dirs, {{ShuffleHandler}} always uses the original {{NM_LOCAL_DIRS}} value in its {{Configuration}} object. So every time {{AllocatorPerContext#confChanged}} is called by {{ShuffleHandler}} after {{LocalDirsHandlerService}}, {{AllocatorPerContext}} need be reinitialized because {{NM_LOCAL_DIRS}} value is changed. This will cause some overhead.
> {code}
>       String newLocalDirs = conf.get(contextCfgItemName);
>       if (!newLocalDirs.equals(savedLocalDirs)) {
> {code}
> So it will be a good improvement to not share the same {{AllocatorPerContext}} instance between {{ShuffleHandler}} and {{LocalDirsHandlerService}}.



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