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https://issues.apache.org/jira/browse/CURATOR-447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16361577#comment-16361577
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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_r167715541
--- Diff:
curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/TreeCache.java
---
@@ -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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