RFR: 8252936: Optimize removal of listeners from ExpressionHelper.Generic [v3]

[John Nader]

On Wed, 14 Apr 2021 12:33:23 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
>
> dannygonzalez has updated the pull request incrementally.

Your points regarding unnecessary default listeners are valid.

The question now is should the work done on this PR be abandoned. It addresses a current performance limitation taking complexity from O(n log n) to O(1). It appears to be well isolated with low risk to backwards compatibility. The reason work was stopped was a concern that the tests should go first in a separate PR.

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