On Tue, 4 Mar 2025 18:23:45 GMT, Andy Goryachev <ango...@openjdk.org> wrote:

>> Root Cause:
>> (Multiple) properties are getting bound to the global 
>> `Platform.accessibilityActive` property. Binding (and I say, accessing) of 
>> properties is not thread-safe.
>> 
>> I also changed the design a bit.  Originally, every symbol in a chart had 
>> its `focusTraversableProperty` bound to `Platform.accessibilityActive` in 
>> order to enable the accessibility navigation across the chart data points.  
>> This is rather inefficient, as the property has to manage (thousands?) of 
>> listeners.
>> 
>> Instead, a single boolean property is added to each chart, with a listener 
>> added to it which iterates over data symbols to toggle the 
>> `focusTraversableProperty` directly.
>> 
>> The exact moment when the new property gets bound is also important, and has 
>> to happen in the FX application thread.
>> 
>> With this change, it is safe to create and populate charts with data in a 
>> background thread.
>> 
>> ---
>> 
>> ## NOTES
>> 
>> 1. It looks like the `Platform.accessibilityActive` property never 
>> transitions back to false  after it transitioned to true.  Some say it is 
>> because there is no mechanism in the platform to get notified which cannot 
>> possibly be true.
>> 2. The javadoc for `Platform.accessibilityActiveProperty()` method 
>> stipulates that "_This method may be called from any thread_" which is 
>> patently not true as the current implementation is simply not thread-safe.
>> 
>> ## Note to the Reviewers
>> 
>> To avoid merge conflicts, the preferred order of integrations:
>> 
>> #1697 
>> #1713 
>> #1717
>
> Andy Goryachev has updated the pull request with a new target base due to a 
> merge or a rebase. The pull request now contains 29 commits:
> 
>  - use subscription
>  - Merge remote-tracking branch 'origin/master' into 
> 8349091.charts.thread.safety
>  - unnecessary
>  - Merge remote-tracking branch 'origin/master' into 
> 8349091.charts.thread.safety
>  - Merge remote-tracking branch 'origin/master' into 
> 8349091.charts.thread.safety
>  - review comments
>  - Merge remote-tracking branch 'origin/master' into 
> 8349091.charts.thread.safety
>  - Merge remote-tracking branch 'origin/master' into 
> 8349091.charts.thread.safety
>  - enabled pie chart test
>  - Merge branch 'master' into 8349091.charts.thread.safety
>  - ... and 19 more: https://git.openjdk.org/jfx/compare/1824db5c...fc40e9d6

I'll do some more testing, but this looks OK to me.

modules/javafx.controls/src/main/java/javafx/scene/chart/Chart.java line 563:

> 561:                     .subscribe((w) -> {
> 562:                         if (w != null) {
> 563:                             // also unsubscribes when appears in a window

Suggestion: Add a comment that this can only happen on the FX app thread, since 
you are relying on that.

-------------

PR Review: https://git.openjdk.org/jfx/pull/1697#pullrequestreview-2658633362
PR Review Comment: https://git.openjdk.org/jfx/pull/1697#discussion_r1980031738

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