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https://issues.apache.org/jira/browse/CURATOR-447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16361579#comment-16361579
 ] 

ASF GitHub Bot commented on CURATOR-447:
----------------------------------------

Github user njhill commented on a diff in the pull request:

    https://github.com/apache/curator/pull/250#discussion_r167715799
  
    --- Diff: 
curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/TreeCache.java
 ---
    @@ -728,13 +710,12 @@ private TreeNode find(String findPath)
         public ChildData getCurrentData(String fullPath)
         {
             TreeNode node = find(fullPath);
    -        if ( node == null || node.nodeState != NodeState.LIVE )
    +        if ( node == null )
             {
                 return null;
             }
             ChildData result = node.childData;
    -        // Double-check liveness after retreiving data.
    -        return node.nodeState == NodeState.LIVE ? result : null;
    +        return result != DEAD ? result : null;
    --- End diff --
    
    Reason was that `isLive` also checks for `null` which isn't necessary here 
(since we're returning `null` anyhow). But no harm in making it consistent.


> TreeCache: Improve memory usage and concurrent update logic
> -----------------------------------------------------------
>
>                 Key: CURATOR-447
>                 URL: https://issues.apache.org/jira/browse/CURATOR-447
>             Project: Apache Curator
>          Issue Type: Improvement
>          Components: Recipes
>    Affects Versions: 3.3.0, 2.12.0
>            Reporter: Nick Hill
>            Priority: Minor
>              Labels: performance
>
> Jira https://issues.apache.org/jira/browse/CURATOR-374 reduced per-node 
> memory usage in {{TreeCache}}. It can be improved further via removal of the 
> {{nodeState}} field - its {{LIVE}} state corresponds exactly to the adjacent 
> {{childData}} field being non-null, and a sentinel {{ChildData}} value can be 
> used for the {{DEAD}} state. This simplification also reduces the room for 
> bugs and state inconsistencies.
> Other improvements included:
> * A further simplification to have {{TreeNode}} extend {{AtomicReference}}, 
> which obviates the need for an explicit {{childData}} field
> * More robust cache update logic (in get-children and get-data event 
> callbacks)
> * Avoid overhead of incrementing/decrementing the {{outstandingOps}} atomic 
> integer post-initialization



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