RFR: 8252936: Optimize removal of listeners from ExpressionHelper.Generic

[Jeanette Winzenburg]

On Thu, 6 Feb 2020 16:22:28 GMT, dannygonzalez <github.com+6702882+dannygonzalez at openjdk.org> wrote:

>> https://bugs.openjdk.java.net/browse/JDK-8185886
>> 
>> Optimisation to ExpressionHelper.Generic class to use Sets rather than Arrays to improve listener removal speed.
>> 
>> This was due to the removal of listeners in TableView taking up to 50% of CPU time on the JavaFX Application thread when scrolling/adding rows to TableViews.
>> 
>> This may alleviate some of the issues seen here:
>> 
>> TableView has a horrific performance with many columns #409
>> https://github.com/javafxports/openjdk-jfx/issues/409#event-2206515033
>> 
>> JDK-8088394 : Huge memory consumption in TableView with too many columns
>> JDK-8166956: JavaFX TreeTableView slow scroll performance
>> JDK-8185887: TableRowSkinBase fails to correctly virtualise cells in horizontal direction
>> 
>> OpenJFX mailing list thread: TableView slow vertical scrolling with 300+ columns
>> https://mail.openjdk.java.net/pipermail/openjfx-dev/2020-January/024780.html
>
> I have signed the Oracle Contributor Agreement today. Have not received back any confirmation yet though.

hmm ... wouldn't the change violate spec of adding listeners:

> If the same listener is added more than once, then it will be notified more than once.

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PR: https://git.openjdk.java.net/jfx/pull/108