Hacktoberfest 2026：维护者为十月标记出来的 issue，仍然开放、适合新手。 浏览 Hacktoberfest issue

`AbstractDataTreeNode.indexOfChild()` is called excessively on large resource tree size

未关闭
  • 哪里不对？
#2,567 0 条评论 0 个 reaction 已指派 0 人 在 GitHub 查看

维护者通常 1 天内回复

还没有人认领这个 Issue。

评估

难度
5/5
预计耗时
一周以上
新手友好度
25/100
Issue 类型
重构
描述清晰度
需要澄清
活跃度
停滞
技术栈
java
领域
performance

调研方向

从 AbstractDataTreeNode.indexOfChild() 和 DeltaDataTree.lookup() 开始，然后检查链接的 heapdump 分析以及 delta-tree 的父节点遍历。在大型资源树上对 lookup 进行基准测试，并比较提出的优化方向。完成的标准是，所选方案在不改变 lookup 行为的情况下减少报告中的 lookup 热点。

由索引模型根据 Issue 内容生成。

描述

enhancement

During analysis of two heapdumps shared here the following issue was discovered as a hotspot that can benefit from optimization:

Performance Data
Metric WITH transitive WITHOUT transitive Ratio
indexOfChild() self time (µs) 70,405,568 35,739,594 2.0×
DeltaDataTree.lookup() (µs) 55,328,734 24,397,133 2.3×
Description

indexOfChild() performs a binary search on a sorted array of child nodes:

protected int indexOfChild(String localName) {
    AbstractDataTreeNode[] nodes = this.children;
    int left = 0, right = nodes.length - 1;
    while (left <= right) {
        int mid = (left + right) / 2;
        int compare = localName.compareTo(nodes[mid].name);
        // ...
    }
    return -1;
}

While the binary search itself is O(log n), DeltaDataTree.lookup() calls indexOfChild() at each path segment level:

public DataTreeLookup lookup(IPath key) {
    int keyLength = key.segmentCount();
    for (DeltaDataTree tree = this; tree != null; tree = tree.parent) {
        AbstractDataTreeNode node = tree.rootNode;
        for (int i = 0; i < keyLength; i++) {
            node = node.childAtOrNull(key.segment(i)); // calls indexOfChild
        }
    }
}

The delta tree chain (tree.parent) can be deep, and each delta layer requires re-traversing the path from root.

The combined indexOfChild() time (70.4 seconds) represents the single largest CPU consumer in the entire build.

Suggested Fix
  1. Compact delta chains more aggressively: The parent chain walk is expensive. More frequent immobilization of the delta tree would reduce the number of layers to traverse.
  2. Cache frequent lookups: If the same resource paths are looked up repeatedly (e.g., project roots, source folders), a small LRU cache on DeltaDataTree.lookup() could avoid repeated traversals.
  3. Consider hybrid data structure: For nodes with many children (> 100), consider switching from sorted array + binary search to a HashMap<String, AbstractDataTreeNode> for O(1) child lookup. This is particularly relevant for directories containing many files (e.g., classpath container folders).
  4. Reduce key.segment(i) overhead: Each call to IPath.segment(i) on Path objects does array access. Ensure paths are not being reconstructed or re-parsed in hot loops.
主要语言
Java
星标
165
派生
174
平均合并
4 天 7 小时
30 天内合并 PR
39

环境准备

从这里开始

  1. 先读完整个 Issue，再读项目的贡献指南。
  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库，在一个分支上完成修改。
  4. 提交 Pull Request，并在描述里引用这个 Issue 编号。

eclipse-platform/eclipse.platform 的其他 Issue

查看 eclipse-platform/eclipse.platform 的全部 Issue

相似的 Issue

更多 Java Issue

把新 issue 发到你的邮箱

精选适合新手参与的 GitHub issue 摘要。