[jira] [Commented] (YARN-2996) Refine some fs operations in FileSystemRMStateStore to improve performance

["Yi Liu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-2996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14263743#comment-14263743 ] 

Yi Liu commented on YARN-2996:
------------------------------

The 3 tests failures are not related.

> Refine some fs operations in FileSystemRMStateStore to improve performance
> --------------------------------------------------------------------------
>
>                 Key: YARN-2996
>                 URL: https://issues.apache.org/jira/browse/YARN-2996
>             Project: Hadoop YARN
>          Issue Type: Improvement
>          Components: resourcemanager
>            Reporter: Yi Liu
>            Assignee: Yi Liu
>         Attachments: YARN-2996.001.patch
>
>
> In {{FileSystemRMStateStore}}, we can refine some fs operations to improve performance:
> *1.* There are several places invoke {{fs.exists}}, then {{fs.getFileStatus}}, we can merge them to save one RPC call
> {code}
> if (fs.exists(versionNodePath)) {
>     FileStatus status = fs.getFileStatus(versionNodePath);
> {code}
> *2.*
> {code}
> protected void updateFile(Path outputPath, byte[] data) throws Exception {
>   Path newPath = new Path(outputPath.getParent(), outputPath.getName() + ".new");
>   // use writeFile to make sure .new file is created atomically
>   writeFile(newPath, data);
>   replaceFile(newPath, outputPath);
> }
> {code}
> The {{updateFile}} is not good too, it write file to _output\_file_.tmp, then rename to _output\_file_.new, then rename it to _output\_file_, we can reduce one rename operation.
> Also there is one unnecessary import, we can remove it.



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