RFR: 8269907 memory leak - Dirty Nodes / Parent removed [v7]

[Michael Strauß]

On Thu, 26 Jan 2023 09:54:25 GMT, Florian Kirmaier <fkirmaier at openjdk.org> wrote:

>> After thinking about this issue for some time, I've now got a solution.
>> I know put the scene in the state it is, before is was shown, when the dirtyNodes are unset, the whole scene is basically considered dirty. 
>> This has the drawback of rerendering, whenever a window is "reshown", but it restores sanity about memory behaviour, which should be considered more important.
>
> Florian Kirmaier has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:
> 
>  - JDK-8269907
>    Added missing changes after merge
>  - Merge remote-tracking branch 'origjfx/master' into JDK-8269907-dirty-and-removed
>    
>    # Conflicts:
>    #	modules/javafx.graphics/src/main/java/com/sun/javafx/tk/Toolkit.java
>    #	modules/javafx.graphics/src/main/java/javafx/scene/Scene.java
>  - Merge remote-tracking branch 'origin/master'
>  - JDK-8269907
>    Removed the sync methods for the scene, because they don't work when peer is null, and they are not necessary.
>  - JDK-8269907
>    Fixed rare bug, causing bounds to be out of sync.
>  - JDK-8269907
>    We now require the rendering lock when cleaning up dirty nodes. To do so, we moved some code required for snapshot into a reusable method.
>  - JDK-8269907
>    The bug is now fixed in a new way. Toolkit now supports registering CleanupListeners, which can clean up the dirty nodes, avoiding memoryleaks.
>  - JDK-8269907
>    Fixing dirty nodes and parent removed, when a window is no longer showing.  This typically happens with context menus.

I've left some comments.

modules/javafx.graphics/src/main/java/com/sun/javafx/tk/Toolkit.java line 420:

> 418:                 new WeakHashMap<>();
> 419:         final Map<TKPulseListener,AccessControlContext> cleanupList =
> 420:                 new WeakHashMap<>();

I wonder why we need `WeakHashMap` here. These maps are short-lived anyway, since they're local variables.

modules/javafx.graphics/src/main/java/com/sun/javafx/tk/Toolkit.java line 494:

> 492:     public void addCleanupListener(TKPulseListener listener) {
> 493:         AccessControlContext acc = AccessController.getContext();
> 494:         cleanupListeners.put(listener,acc);

Access to `cleanupListeners` is not synchronized on `this` here, but it is synchronized in L426.
You should either synchronize each and every access, or none of it.

modules/javafx.graphics/src/main/java/javafx/scene/Scene.java line 745:

> 743:     private void checkCleanDirtyNodes() {
> 744:         if(!cleanupAdded) {
> 745:             if((window.get() == null || !window.get().isShowing()) && dirtyNodesSize > 0) {

Minor: space after `if`.
You could also reduce nesting by consolidating the two separate conditions.

modules/javafx.graphics/src/main/java/javafx/scene/Scene.java line 2112:

> 2110:      **************************************************************************/
> 2111: 
> 2112:     private void windowForSceneChanged(Window oldWindow, Window window) {

This change doesn't seem necessary.

modules/javafx.graphics/src/main/java/javafx/scene/Scene.java line 2129:

> 2127:     }
> 2128: 
> 2129:     private final ChangeListener<Boolean> sceneWindowShowingListener = (p, o, n) -> {checkCleanDirtyNodes(); } ;

Minor: should be no space before `;`.
You could also remove the curly braces.

tests/system/src/test/java/test/javafx/scene/DirtyNodesLeakTest.java line 35:

> 33: import junit.framework.Assert;
> 34: import org.junit.BeforeClass;
> 35: import org.junit.Test;

Since this is a new class, you should use the JUnit5 API.

tests/system/src/test/java/test/javafx/scene/DirtyNodesLeakTest.java line 44:

> 42: import static test.util.Util.TIMEOUT;
> 43: 
> 44: public class DirtyNodesLeakTest {

Since this tests dirty nodes of a `Scene`, maybe you could use a name like `Scene_dirtyNodesLeakTest`?

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PR: https://git.openjdk.org/jfx/pull/584