[jira] [Commented] (HADOOP-15343) NetworkTopology#getLoc should exit loop earlier rather than traverse all children

["Rushabh S Shah (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-15343?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16414246#comment-16414246 ] 

Rushabh S Shah commented on HADOOP-15343:
-----------------------------------------

Does it make sense to backport HADOOP-12185 to branch-2.7 ?
HADOOP-12185 is trying to solve the in-efficiencies in adding/getting/removing nodes from {{NetworkTopology}}.
I understand this jira is subset of HADOOP-12185 but doesn't hurt getting more performance benefits.


> NetworkTopology#getLoc should exit loop earlier rather than traverse all children
> ---------------------------------------------------------------------------------
>
>                 Key: HADOOP-15343
>                 URL: https://issues.apache.org/jira/browse/HADOOP-15343
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: performance
>    Affects Versions: 2.7.6
>            Reporter: He Xiaoqiao
>            Priority: Major
>              Labels: performance
>         Attachments: HADOOP-15343-branch-2.7.001.patch
>
>
> NetworkTopology#getLoc return a proper node after traverse ALL children of current {{InnerNode}} even if it has found expected result, based on branch-2.7. This issue may lead some performance loss especially for a large & busy cluster and many nodes under a rack. I think it should exit loop earlier rather than traverse all children of {{InnerNode}}.
> {code:java}
>     private Node getLoc(String loc) {
>       if (loc == null || loc.length() == 0) return this;
>             
>       String[] path = loc.split(PATH_SEPARATOR_STR, 2);
>       Node childnode = null;
>       for(int i=0; i<children.size(); i++) {
>         if (children.get(i).getName().equals(path[0])) {
>           childnode = children.get(i);
>         }
>       }
>       if (childnode == null) return null; // non-existing node
>       if (path.length == 1) return childnode;
>       if (childnode instanceof InnerNode) {
>         return ((InnerNode)childnode).getLoc(path[1]);
>       } else {
>         return null;
>       }
>     }
> {code}



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