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https://issues.apache.org/jira/browse/YARN-3491?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14526271#comment-14526271
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zhihai xu commented on YARN-3491:
---------------------------------
I uploaded a new patch YARN-3491.003 patch for review.
I think the new patch YARN-3491.003 is better than previous solutions.
It can solve the race condition "if a directory goes from bad to good." in
[~wilfreds]'s comment.
I add a small feature in DirectoryCollection.java:{{DirsChangeListener}}.
{{ResourceLocalizationService}} can register {{DirsChangeListener}} for
localDirs and logDirs.
Once DirectoryCollection#localDirs is changed in {{checkDirs}},
{{ResourceLocalizationService}} will get callback
DirsChangeListener#onDirsChanged, which will call {{getInitializedLocalDirs}}
and {{getInitializedLogDirs}}
> PublicLocalizer#addResource is too slow.
> ----------------------------------------
>
> Key: YARN-3491
> URL: https://issues.apache.org/jira/browse/YARN-3491
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: nodemanager
> Affects Versions: 2.7.0
> Reporter: zhihai xu
> Assignee: zhihai xu
> Priority: Critical
> Attachments: YARN-3491.000.patch, YARN-3491.001.patch,
> YARN-3491.002.patch, YARN-3491.003.patch
>
>
> Based on the profiling, The bottleneck in PublicLocalizer#addResource is
> getInitializedLocalDirs. getInitializedLocalDirs call checkLocalDir.
> checkLocalDir is very slow which takes about 10+ ms.
> The total delay will be approximately number of local dirs * 10+ ms.
> This delay will be added for each public resource localization.
> Because PublicLocalizer#addResource is slow, the thread pool can't be fully
> utilized. Instead of doing public resource localization in
> parallel(multithreading), public resource localization is serialized most of
> the time.
> And also PublicLocalizer#addResource is running in Dispatcher thread,
> So the Dispatcher thread will be blocked by PublicLocalizer#addResource for
> long time.
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