On Wed, 17 Jun 2026 22:06:06 GMT, Nir Lisker <[email protected]> wrote:
>> This PR is an optimization for `Node.styleClass` and `Parent.stylesheets`. >> Instead of always initializing both properties with an empty list, we are >> creating (therefore allocating) the list on the first access instead. >> Similar to many other lazy properties. >> >> Why? >> - `Parent.getStylesheets()` is very rarely used by developers and JavaFX >> code. So this list is very often completely unused and empty. Most >> developers usually only add stylesheets at the `Scene` >> - `Node.getStyleClass()` is usually not used (empty) for layout containers >> such as `Pane` or `Group` or shapes. A JavaFX App usually consists of a good >> amount of such containers (or shapes) >> >> So that our CSS code is not initializing both lists on access, I added >> related `NodeHelper` and `ParentHelper` methods to return `null` when both >> lists were not initialized and therefore used. Otherwise we return the list >> as before. >> This will save us some memory and allocation, which is both good for the >> memory consumption but also for `Node` / `Parent` creation (time). >> >> Added documentation and tests. Will do some measurements with some apps very >> soon and attach it here. >> >> --- >> >> # Benchmarks >> >> I wrote a very small scene graph analyzer snippet to measure the memory gain. >> Feel free to test this on your own apps! >> 1. Get the `SceneGraphAnalyzer` here: >> [SceneGraphAnalyzer](https://gist.github.com/Maran23/38beca5b043e547e1a84749e3162c0b2) >> 2. Add this code to your `Scene` and press the shortcut `F12` when all of >> the UI is loaded: >> >> scene.setOnKeyPressed(event -> { >> if (event.getCode() == KeyCode.F12) { >> var analyzer = new SceneGraphAnalyzer(); >> var res = analyzer.analyze(scene); >> res.print(); >> } >> }); >> >> 3. If you have a modular app, add the following VM argument: `--add-opens >> javafx.graphics/javafx.scene=yourapp` >> >> ## Projects >> >> 1. Tested with >> [JFXCentral](https://github.com/dlsc-software-consulting-gmbh/jfxcentral2) >> >> >> ╔══════════════════════════════════════════════════╗ >> ║ Scene Graph Analysis ║ >> ╠══════════════════════════════════════════════════╣ >> ║ Total nodes: 654 ║ >> ║ ├─ Parent nodes: 388 ║ >> ║ └─ Leaf nodes: 266 ║ >> ╠══════════════════════════════════════════════════╣ >> ║ Null styleClass: 19 / 654 ( 2.9%) ║ >> ║ Null stylesheets: 3... > > modules/javafx.graphics/src/main/java/javafx/scene/Node.java line 1371: > >> 1369: } >> 1370: } >> 1371: return buf.toString(); > > If you prefer: > Suggestion: > > return switch (size()) { > case 0 -> ""; > case 1 -> get(0); > default -> { > StringBuilder buf = new > StringBuilder(); > for (int i = 0; i < size(); i++) { > buf.append(get(i)); > if (i + 1 < size()) { > buf.append(' '); > } > } > yield buf.toString(); > } > }; or a regular switch(size()) to minimize the diff ------------- PR Review Comment: https://git.openjdk.org/jfx/pull/2191#discussion_r3437518989
