ASF GitHub Bot commented on CURATOR-447:

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

    --- Diff: 
    @@ -704,8 +687,7 @@ private TreeNode find(String findPath)
                     TreeNode childNode = entry.getValue();
                     ChildData childData = childNode.childData;
    -                // Double-check liveness after retreiving data.
    --- End diff --
    The reason I removed it is that unlike before it's not really "double" 
checking anymore against the separate `nodeState` field, there's only a single 
check for liveness which is now implicit in the value of `childData`. But I 
could well have misinterpreted the reason for comment, no problem with leaving 
it in!

> 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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