UI freezes with latest ScalaFX requiring Java greater than 21 to run the JFXApp3 - inexplicable infinite loop

[sjbiaga]

Compiler version

3.7.2-RC1

Java version

openjdk-bin-25

ScalaFX version

24.0.0-R35

Minimized example

Latest ScalaFX requires Java greater than 21.
My UI works with version 3.7.1.
After update to 3.7.2-RC1, it somehow freezes after a drag event.

The communication from the UI to the background fiber is done with cats.effect.std.Dispatcher[IO]#unsafeRunAndForget from a scalafx.scene.canvas.Canvas.

Expectation

To work smoothly just like for 3.7.1.

[Gedochao]

@sjbiaga can you provide reproduction steps and/or a minimized code example?

[sjbiaga]

MWE REPL session:

root@localhost ~ $ scala-cli repl -S 3.7.2-RC1
WARNING: A terminally deprecated method in sun.misc.Unsafe has been called
WARNING: sun.misc.Unsafe::objectFieldOffset has been called by scala.runtime.LazyVals$ (file:/home/sjb/.cache/coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala3-library_3/3.7.2-RC1/scala3-library_3-3.7.2-RC1.jar)
WARNING: Please consider reporting this to the maintainers of class scala.runtime.LazyVals$
WARNING: sun.misc.Unsafe::objectFieldOffset will be removed in a future release
WARNING: A restricted method in java.lang.System has been called
WARNING: java.lang.System::load has been called by org.jline.nativ.JLineNativeLoader in an unnamed module (file:/home/sjb/.cache/coursier/v1/https/repo1.maven.org/maven2/org/jline/jline-native/3.29.0/jline-native-3.29.0.jar)
WARNING: Use --enable-native-access=ALL-UNNAMED to avoid a warning for callers in this module
WARNING: Restricted methods will be blocked in a future release unless native access is enabled

Welcome to Scala 3.7.2-RC1 (25-beta, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.
                                                                                                                               
scala> case class Path(depth: Int, parent: Option[Path]):
     |   def make: Path = Path(depth+1, Some(this))
     |   object O:
     |     @annotation.tailrec
     |     def apply(): Unit =
     |       if depth > 1
     |       then
     |         println(depth->parent.get.depth)
     |         parent.get.O.apply()
     | 
// defined case class Path
                                                                                                                               
scala> var path = Path(1, None)
var path: Path = Path(1,None)
                                                                                                                               
scala> path.O()
                                                                                                                               
scala> path = path.make
path: Path = Path(2,Some(Path(1,None)))
                                                                                                                               
scala> path.O()
(2,1)

[prolativ]

Bisect script friendly minimization (for bisect run command):

class Path(action: () => Unit, parent: Option[Path]):
  object O:
    def apply(): Unit =
      action()

      parent match
        case Some(p) =>
          p.O.apply()
        case None =>

@main def main(): Unit =
  var counter = 0
  val fun = () => {
    counter += 1
    if counter > 2 then sys.exit(1)
  }
  val path = Path(fun, Some(Path(fun, None)))
  path.O()

Unfortunately I'm having some problems with running the bisect script on my machine