I'm trying (mostly in vain) to optimise the startup time of my app. It takes about a second to build the main GUI via FXMLLoader.load() - probably because the GUI is getting a little bit complex but I think mostly because it's all running interpreted, as it's one of the first things the app does. Later loads of the same GUI take more like 100-200msec, presumably because HotSpot went in and compiled it. But that's kind of useless for me. It's the first load that counts.
So I figured I'd bring up a stage of the right size early with just a logo and a loading indicator, and load the root Node of my UI on a background thread so the user has something to look at for a moment whilst it's hauling itself into memory. My first attempt was to show the splash and then load the UI. Didn't work of course, because the UI thread didn't get a chance to render. So then I put it inside a Platform.runLater which also didn't work, the splash didn't appear quickly enough. So then I tried putting it in a background thread. This got the right splash behaviour but it didn't work out of the box: my GUI has tooltips and context menus in it. These attempt to construct a Scene at load time, which of course fails because it's not on the GUI thread. Once I commented those out, I got the behaviour I wanted, but of course at the cost of features. Given that these Scene's are not being rendered as they're not visible or interactable, what's the reason they have to be built on the UI thread? Also does anyone have any advice for making JFX8 apps that start really fast? I tried parallelising most of the work my app is doing at startup and annoyingly it hardly helped at all. Not sure why yet: perhaps the JVM or the operating system is busy using the other core so all my threads get scheduled onto the same chip.
