On Mon, 7 Sep 2026 00:31:41 GMT, Marius Hanl <[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 | >> +---------------------------------------------------------------+ >> | Nodes: 654 total, 388 parents, 266 leaves | >> +---------------------------------------------------------------+ >> | Field Null Total % N/A Avg Saved | >> | ------------------------------------------... > > Marius Hanl has updated the pull request with a new target base due to a > merge or a rebase. The incremental webrev excludes the unrelated changes > brought in by the merge/rebase. The pull request contains eight additional > commits since the last revision: > > - Merge branch 'master' of https://github.com/openjdk/jfx into > 8386663-Stylesheet/StyleClass-list-should-be-lazily-initialized > - remove doc > - review comments > - improve tests > - Merge branch 'master' of https://github.com/openjdk/jfx into > 8386663-Stylesheet/StyleClass-list-should-be-lazily-initialized > - MenuItem toString() should also use the new styleClass way. > > TwoLevelFocusListBehavior was very weirdly relying on the toString() > behavior > - Move styleClass.toString into Node.toString() > - 8386663: Stylesheet/StyleClass list should be lazily initialized I updated the `SceneGraphAnalyzer` a bit, also because I use it to measure the amount of CSS styleHelper for my CSS PR (and some upcoming changes). Found out that I measured the footprint wrong, we actually save more bytes than I originally thought. The way I know measure it now is by using: `GraphLayout.parseInstance(...).toFootprint();` and put in an instance of `TrackableObservableList`. As it registers a listener inside the constructor (which will initialize the `listenerHelper`), the footprint is a bit higher. ------------- PR Comment: https://git.openjdk.org/jfx/pull/2191#issuecomment-5569644087
