IndexOutOfBoundsException in Parent::updateCachedBounds when visibility changes
Dean Wookey
wookey.dean at gmail.com
Wed Jun 25 09:06:38 UTC 2025
Hi Everyone,
We've also been experiencing this problem over the years. It seems to be
related to JDK-8198577.
Once it goes wrong, each pulse hits the issue repeated meaning it can
never escape. It's rare, but extremely disruptive when it does occur
because the user loses what they've been working on and has to restart the
app.
I've tried really hard to figure out the conditions this happens in. I
don't think it's a multiple thread issue (although for some people it
almost certainly could be triggered that way) because we've put conditional
breakpoints that trigger whenever anything that could affect dirty children
is done off the app thread. We've got assert
Platform.isFXApplicationThread() all over our app to make sure the
threading is happening properly.
What I think is happening is that getChildTransformedBounds which is
being called inside the updateCachedBounds loop, can in some rare cases,
end up triggering a call to updateCachedBounds on the same node. Basically
updateCachedBounds can call itself recursively. This is a snipped from
Parent.java in updateCachedBounds.
// this checks the newly added nodes first, so if dirtyNodes is the
// whole children list, we can end early
for (int i = dirtyNodes.size() - 1; remainingDirtyNodes > 0; --i) {
final Node node = dirtyNodes.get(i);
if (node.boundsChanged) {
// assert node.isVisible();
node.boundsChanged = false;
--remainingDirtyNodes;
tmp = getChildTransformedBounds(node,
BaseTransform.IDENTITY_TRANSFORM, tmp);
In the code above, if this gets called recursively through
getChildTransformedBounds, then node.boundsChanged will change to false for
all the nodes which stops remainingDirtyNodes from being updated and i
eventually goes negative.
We tried to fix the scene graph when this happens by catching the
exception in the Thread.setDefaultUncaughtExceptionHandler but it didn't
work. Maybe Christopher's suggested fix would work, but as Kevin says "It
needs to be tested to ensure that when we get the AIOOBE that we can
recover. It wouldn't solve anything if we catch and log that exception only
to have it fail shortly after because the scene graph isn't in a good state
(I don't know whether that would be the case, but it's something that needs
to be checked)."
Here's how we tried to fix the scene graph when we caught the error. The
"Fixing IOB Issue" log gets hit all the time, but it doesn't find any
problems, and in the next pulse it hits the problem again with various
different stack traces until it settles on one. In our latest example of
the error, it first occurred during a Platform.runLater and not during the
pulse, but then all subsequent issues happen during the pulse.
protected static void checkSpecialException(Throwable t) {
if (t instanceof IndexOutOfBoundsException) {
fixIndexOutOfBounds(t);
}
}
public static void fixIndexOutOfBounds(Throwable throwable) {
FXUtilities.log(EmbraceDesktop.class, org.slf4j.event.Level.INFO,
"Fixing IOB Issue");
try {
Field dirtyChildrenCountField =
Parent.class.getDeclaredField("dirtyChildrenCount");
dirtyChildrenCountField.setAccessible(true);
Field dirtyChildrenField =
Parent.class.getDeclaredField("dirtyChildren");
dirtyChildrenField.setAccessible(true);
Set<Scene> apps = applicationManager.getApplications();
ArrayList<Node> brokenStack = new ArrayList<>();
for (Scene s: apps) {
fixTreeRecursive(dirtyChildrenCountField,
dirtyChildrenField, s.getRoot(), brokenStack);
}
if (brokenStack.size() > 0) {
StringBuilder errorStack = new StringBuilder();
for (Node n: brokenStack) {
errorStack.append(n.getClass().getSimpleName() + " "
+ String.join( ",", n.getStyleClass())).append("\n");
}
EmbraceAnalytics.logCrash("Index out of bounds
crash",errorStack.toString(), throwable);
}
}
catch (Throwable t2) {
FXUtilities.log(EmbraceDesktop.class,
org.slf4j.event.Level.ERROR, "Exception while fixing tree", t2);
}
}
protected static boolean fixTreeRecursive(Field
dirtyChildrenCountField, Field dirtyChildrenField, Parent parent,
ArrayList<Node> brokenStack) throws IllegalAccessException {
List<?> dirtyChildren = (List<?>) dirtyChildrenField.get(parent);
int dirtyChildrenCount = (int)
dirtyChildrenCountField.get(parent);
if (dirtyChildren != null) {
if (dirtyChildrenCount > dirtyChildren.size()) {
FXUtilities.log(EmbraceDesktop.class,
org.slf4j.event.Level.ERROR, "Offending node1 was " +
parent.getClass().getSimpleName());
dirtyChildrenCountField.set(parent,
dirtyChildren.size());
brokenStack.add(parent);
return true;
}
}
else {
if (parent.getChildrenUnmodifiable().size() <
dirtyChildrenCount) {
FXUtilities.log(EmbraceDesktop.class,
org.slf4j.event.Level.ERROR, "Offending node2 was " +
parent.getClass().getSimpleName());
dirtyChildrenCountField.set(parent,
parent.getChildrenUnmodifiable().size());
brokenStack.add(parent);
return true;
}
}
for (Node n: parent.getChildrenUnmodifiable()) {
if (n instanceof Parent) {
boolean error =
fixTreeRecursive(dirtyChildrenCountField, dirtyChildrenField, (Parent)n,
brokenStack);
if (error) {
brokenStack.add(parent);
FXUtilities.log(EmbraceDesktop.class,
org.slf4j.event.Level.ERROR, "Parent was " +
parent.getClass().getSimpleName());
}
return error;
}
}
return false;
}
I think we should we should put the index check potential fix in and log
when it happens. As far as we can tell, if this issue gets hit, it's
catastrophic 100% of the time. The fix might resolve the issue. It can't
really make it any worse. Another thing we should do is add a check for
recursive entry to that method and log when that occurs. That's (I think)
the real issue, and without a stack trace of that, it's hard to find the
root cause.
I don't know if anyone else has experienced this issue and has
insights/workarounds?
Dean
On Mon, Mar 24, 2025 at 5:22 PM Christopher Schnick <crschnick at xpipe.io>
wrote:
> Hello,
>
> We encountered an issue after updating our application implementation to
> frequently change the visibility of nodes. We are essentially now running
> an implementation that very frequently changes the visibility of various
> children nodes based on when they are needed and shown. When the user
> performs a lot of actions, the visibility of many nodes will be changed
> rapidly.
>
> For that, there are many listeners in place that listen for bounds changes
> of nodes to recheck whether they need to be made visible or not. All the
> visibility changes are queued up, so they are not immediately done in the
> listener after any bounds changes of parents. They are all properly done on
> the platform thread with runLater. When this implementation is running on
> many client systems, we sometimes receive an error report with an exception
> that looks something like this:
>
> java.lang.IndexOutOfBoundsException: Index -1 out of bounds for length 2
> at
> java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:100)
> at
> java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:106)
> at
> java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:302)
> at java.base/java.util.Objects.checkIndex(Objects.java:365)
> at java.base/java.util.ArrayList.get(ArrayList.java:428)
> at
> javafx.base at 25-ea/com.sun.javafx.collections.ObservableListWrapper.get
> (ObservableListWrapper.java:88)
> at
> javafx.base at 25-ea/com.sun.javafx.collections.VetoableListDecorator.get
> (VetoableListDecorator.java:326)
> at javafx.graphics at 25-ea/javafx.scene.Parent.updateCachedBounds
> (Parent.java:1769)
> at javafx.graphics at 25-ea/javafx.scene.Parent.recomputeBounds
> (Parent.java:1713)
> at javafx.graphics at 25-ea/javafx.scene.Parent.doComputeGeomBounds
> (Parent.java:1566)
> at javafx.graphics at 25-ea/javafx.scene.Parent$1.doComputeGeomBounds
> (Parent.java:116)
> at
> javafx.graphics at 25-ea/com.sun.javafx.scene.ParentHelper.computeGeomBoundsImpl
> (ParentHelper.java:84)
> at
> javafx.graphics at 25-ea/com.sun.javafx.scene.layout.RegionHelper.superComputeGeomBoundsImpl
> (RegionHelper.java:78)
> at
> javafx.graphics at 25-ea/com.sun.javafx.scene.layout.RegionHelper.superComputeGeomBounds
> (RegionHelper.java:62)
> at
> javafx.graphics at 25-ea/javafx.scene.layout.Region.doComputeGeomBounds
> (Region.java:3301)
> at
> javafx.graphics at 25-ea/javafx.scene.layout.Region$1.doComputeGeomBounds
> (Region.java:166)
> at
> javafx.graphics at 25-ea/com.sun.javafx.scene.layout.RegionHelper.computeGeomBoundsImpl
> (RegionHelper.java:89)
> at
> javafx.graphics at 25-ea/com.sun.javafx.scene.NodeHelper.computeGeomBounds
> (NodeHelper.java:101)
> at javafx.graphics at 25-ea/javafx.scene.Node.updateGeomBounds
> (Node.java:3908)
> at javafx.graphics at 25-ea/javafx.scene.Node.getGeomBounds
> (Node.java:3870)
> at javafx.graphics at 25-ea/javafx.scene.Node.getLocalBounds
> (Node.java:3818)
> at javafx.graphics at 25-ea/javafx.scene.Node.updateTxBounds
> (Node.java:3972)
> at javafx.graphics at 25-ea/javafx.scene.Node.getTransformedBounds
> (Node.java:3764)
> at javafx.graphics at 25-ea/javafx.scene.Node.updateBounds(Node.java:828)
> at javafx.graphics at 25-ea/javafx.scene.Parent.updateBounds
> (Parent.java:1900)
> at javafx.graphics at 25-ea/javafx.scene.Scene$ScenePulseListener.pulse
> (Scene.java:2670)
> at javafx.graphics at 25-ea/com.sun.javafx.tk.Toolkit.runPulse
> (Toolkit.java:380)
> at javafx.graphics at 25-ea/com.sun.javafx.tk.Toolkit.firePulse
> (Toolkit.java:401)
> at
> javafx.graphics at 25-ea/com.sun.javafx.tk.quantum.QuantumToolkit.pulse
> (QuantumToolkit.java:592)
> at
> javafx.graphics at 25-ea/com.sun.javafx.tk.quantum.QuantumToolkit.pulse
> (QuantumToolkit.java:572)
> at
> javafx.graphics at 25-ea/com.sun.javafx.tk.quantum.QuantumToolkit.pulseFromQueue
> (QuantumToolkit.java:565)
> at
> javafx.graphics at 25-ea/com.sun.javafx.tk.quantum.QuantumToolkit.lambda$runToolkit$6
> (QuantumToolkit.java:346)
> at
> javafx.graphics at 25-ea/com.sun.glass.ui.InvokeLaterDispatcher$Future.run$$$capture
> (InvokeLaterDispatcher.java:95)
> at
> javafx.graphics at 25-ea/com.sun.glass.ui.InvokeLaterDispatcher$Future.run
> (InvokeLaterDispatcher.java)
>
> The index out of bounds is not always the same, there are various
> variations of this. It happens on all operating systems. It seems like
> there is a very specific scenario where an index can be out of bounds. This
> happens very rarely, like only a few times out of some hundred application
> runs, so I tried my best at forcing it to reproduce.
>
> The following reproducer works most of the time, but it might have to be
> run multiple times. I am aware that it eventually results in a
> StackOverflow, but that was the best way to force it reliably, by just
> continuously spamming visibility changes to eventually encounter this rare
> issue. But I want to emphasize that the same error also occurs naturally
> when not being forced like this, but it is just a lot more rare. So the
> StackOverflow in the reproducer has nothing to do with this issue, it also
> happens later on.
>
> import javafx.application.Application;import javafx.scene.Scene;import javafx.scene.control.Button;import javafx.scene.layout.Region;import javafx.scene.layout.StackPane;import javafx.scene.layout.VBox;import javafx.stage.Stage;
> import java.io.IOException;
> public class ParentBoundsBug extends Application {
>
> @Override public void start(Stage stage) throws IOException {
> Scene scene = new Scene(createContent(), 640, 480);
> stage.setScene(scene);
> stage.show();
> stage.centerOnScreen();
> }
>
> private Region createContent() {
> var b1 = new Button("Click me!");
> var b2 = new Button("Click me!");
> var vbox = new VBox(b1, b2);
> b1.boundsInParentProperty().addListener((observable, oldValue, newValue) -> {
> vbox.setVisible(!vbox.isVisible());
> });
> b2.boundsInParentProperty().addListener((observable, oldValue, newValue) -> {
> vbox.setVisible(!vbox.isVisible());
> });
> vbox.boundsInParentProperty().addListener((observable, oldValue, newValue) -> {
> vbox.setVisible(!vbox.isVisible());
> });
>
> var stack = new StackPane(vbox, new StackPane());
> stack.boundsInParentProperty().addListener((observable, oldValue, newValue) -> {
> vbox.setVisible(!vbox.isVisible());
> });
> return stack;
> }
>
> public static void main(String[] args) {
> launch();
> }
> }
>
>
> It doesn't necessarily have something to do with running the visibility
> change directly in the listener, our application does a runLater to change
> the visibility state, still with the same results. To properly debug this,
> you will have to launch the reproducer with a bigger stack size like -Xss8m
> to increase the chance that it occurs. Then, you can just set a breakpoint
> at jdk.internal.util.Preconditions:302, and wait for it to trigger the OOB
> eventually.
>
> This problem is currently the biggest JavaFX issue for us as it breaks the
> layout and usually requires a restart to fix.
>
> Looking at the bounds calculation code, the list index bounds check is
> very optimistic in that it doesn't check any indices and relies on multiple
> assumtions to hold. So if it is very difficult to find the cause, a simple
> index bounds check for the list access would also work fine.
>
> Best
> Christopher Schnick
>
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