jfx 8293444: Creating ScrollPane with same content component causes memory leak

Using Weak*Listeners eliminates the memory leak.

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Issue

JDK-8293444: Creating ScrollPane with same content component causes memory leak

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Sep 15 '22 17:09 andy-goryachev-oracle

:wave: Welcome back angorya! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

Sep 15 '22 17:09 bridgekeeper[bot]

Webrevs

Sep 15 '22 21:09 mlbridge[bot]

/reviewers 2

Sep 16 '22 16:09 kevinrushforth

@kevinrushforth The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 2 (with at least 1 Reviewer, 1 Author).

Sep 16 '22 16:09 openjdk[bot]

A small comment about the memory test with JMemoryBuddy. Instead of this:

<code>
List<WeakReference> refs = ...
WeakReference a = b;
refs.add(a);
<code>
for (WeakReference<ScrollPane> ref : refs) {
       JMemoryBuddy.checkCollectable(ref);
}

It is more readable this way:

JMemoryBuddy.memoryTest(checker -> {
  <code>
  checker.setAsReferenced(objects);
  checker.assertCollectable(b);
});

Sep 28 '22 10:09 FlorianKirmaier

A small comment about the memory test with JMemoryBuddy.

Thank you for suggestion. I will definitely use it in other tests! Here it won't work because in the part of the test one instance is expected to remain uncollected.

Sep 28 '22 17:09 andy-goryachev-oracle

if you use checker.setAsReferenced(object) then the specified object won't be collected for the current test. And there is also the statement assertNotCollectable() to check the reverse.

The method "checkCollectable/assertCollectable" is very slow in the negative case (but reliable in the positive case) The method "checkNotCollectable/<assertNotCollectable" should be used, if it's expected that the object is not collectable - otherwise the test will be quite slow.

Sep 28 '22 20:09 FlorianKirmaier

@FlorianKirmaier : I am not sure if using JMemoryBuddy.memoryTest results in a clearer or more concise code, given the nature of testScrollPaneObjLeakWhenUsedSameContent().

BTW, MemoryTestAPI names are a bit confusing: "assert*Collectable" suggests assertion is done at the point when these calls are made, though it looks like they just add a reference the an internal list. Also, assertCollectable might want to skip creation of a WeakReference if the object passed to it is already a WeakReference.

With your permission, I would like to keep this test as is.

Sep 28 '22 21:09 andy-goryachev-oracle

Of course, you can keep it this way.

The point of JMemoryBuddy.memoryTest is, that the user doesn't have to fiddle around with WeakReferences. For the record, your test might look like this (not tested):

    @Test
    public void testScrollPaneObjLeakWhenUsedSameContent() {
        JMemoryBuddy.memoryTest(() -> {
            BorderPane bp = new BorderPane();

            Stage stage = new Stage();
            stage.setScene(new Scene(bp));
            stage.show();

            Label content = new Label("content");

            ScrollPane sp1 = new ScrollPane(content);
            bp.setCenter(sp1);
            Toolkit.getToolkit().firePulse();

            ScrollPane sp2 = new ScrollPane(content);
            bp.setCenter(sp2);
            Toolkit.getToolkit().firePulse();

            bp.setCenter(null);
            Toolkit.getToolkit().firePulse();

            // When the label is still referenced, then only one ScrollPane should stay which is its parent
            checker.setAsReferenced(label)
            checker.assertCollectable(sp1)
            checker.assertNotCollectable(sp2)
        });
    }

    @Test
    public void testScrollPaneObjLeakWhenUsedSameContent() {
        JMemoryBuddy.memoryTest(() -> {
            BorderPane bp = new BorderPane();

            Stage stage = new Stage();
            stage.setScene(new Scene(bp));
            stage.show();

            Label content = new Label("content");

            ScrollPane sp1 = new ScrollPane(content);
            bp.setCenter(sp1);
            Toolkit.getToolkit().firePulse();

            ScrollPane sp2 = new ScrollPane(content);
            bp.setCenter(sp2);
            Toolkit.getToolkit().firePulse();

            bp.setCenter(null);
            Toolkit.getToolkit().firePulse();

            // IF our label is gone, both scrollpanes shold be collectable
            checker.assertCollectable(sp1)
            checker.assertCollectable(sp2)
        });
    }

I think only the first test is the important one.

Sep 29 '22 08:09 FlorianKirmaier

Thank you for clarifications, @FlorianKirmaier

Sep 29 '22 16:09 andy-goryachev-oracle

@andy-goryachev-oracle This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8293444: Creating ScrollPane with same content component causes memory leak

Reviewed-by: kcr, arapte

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 8 new commits pushed to the master branch:

cc00c8d5c7a73b9d9bc7c292ad51f8af9e63ff78: 8293795: [Accessibility] [Win] [Narrator] Exceptions when deleting text with continous key press in TextArea and TextField
35675c8d27d54a26059b182614e18152794dbcec: 8293971: Loading new Media from resources can sometimes fail when loading from FXML
03569b719b9d838d643dc4514971b06617275e86: 8293883: Add tests/.classpath (Eclipse)
82db6cc342e7de4391f14c70877e77b0e52fbfff: 8289541: Update ICU4C to 71.1
7c6a54d41945a21d2a4f0eceae56b5ba3df9f39f: 8293839: Documentation memory consistency effects of runLater
a27840e8fd7e79b1692488e4de7f6f5fdb930cf4: 8293368: GitHub Workflows security hardening
5e4552db7389d93829e6ecfc61936ccad75c56c2: 8089280: horizontal scrollbar should never become visible in TableView with constrained resize policy
cef583eef41aff3db55542d5e90423eec5601f41: 8293214: Add support for Linux/LoongArch64

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Oct 04 '22 16:10 openjdk[bot]

/integrate

Oct 04 '22 17:10 andy-goryachev-oracle

@andy-goryachev-oracle Your change (at version 0b22c2c958c7d996f33571c1c5ed269bf8ce2063) is now ready to be sponsored by a Committer.

Oct 04 '22 17:10 openjdk[bot]

/sponsor

Oct 04 '22 18:10 kevinrushforth

Going to push as commit 337c78183be84a3420691f615096b54a68ac4300. Since your change was applied there have been 8 commits pushed to the master branch:

cc00c8d5c7a73b9d9bc7c292ad51f8af9e63ff78: 8293795: [Accessibility] [Win] [Narrator] Exceptions when deleting text with continous key press in TextArea and TextField
35675c8d27d54a26059b182614e18152794dbcec: 8293971: Loading new Media from resources can sometimes fail when loading from FXML
03569b719b9d838d643dc4514971b06617275e86: 8293883: Add tests/.classpath (Eclipse)
82db6cc342e7de4391f14c70877e77b0e52fbfff: 8289541: Update ICU4C to 71.1
7c6a54d41945a21d2a4f0eceae56b5ba3df9f39f: 8293839: Documentation memory consistency effects of runLater
a27840e8fd7e79b1692488e4de7f6f5fdb930cf4: 8293368: GitHub Workflows security hardening
5e4552db7389d93829e6ecfc61936ccad75c56c2: 8089280: horizontal scrollbar should never become visible in TableView with constrained resize policy
cef583eef41aff3db55542d5e90423eec5601f41: 8293214: Add support for Linux/LoongArch64

Your commit was automatically rebased without conflicts.

Oct 04 '22 18:10 openjdk[bot]

@kevinrushforth @andy-goryachev-oracle Pushed as commit 337c78183be84a3420691f615096b54a68ac4300.

:bulb: You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

Oct 04 '22 18:10 openjdk[bot]