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

[Kevin Rushforth]

On Thu, 10 Sep 2020 09:48:07 GMT, yosbits <github.com+7517141+yososs at openjdk.org> wrote:

>> Thanks @kevinrushforth, I've changed the title.
>
> I have found that fixing this rudimentary problematic code alleviates your problem.
> 
> **This fix will reduce CPU usage by about 1/3 without your changes.**
> **This fix improves performance in many widespread use cases.**
> 
> However, I'm wondering how to report the problem. Should it be handled in this issue? Should I deal with a new issue for a rudimentary issue?
> 
> @kevinrushforth What should i do?
> 
> https://github.com/openjdk/jfx/blob/22d4343fe8563c2931910b98e8f18c6fd4a48f05/modules/javafx.base/src/main/java/com/sun/javafx/collections/ObservableListWrapper.java#L170-L206
> 
> Rewritten so that BitSet is not used.
>  Java
>     @Override
>     public boolean removeAll(Collection<?> c) {
>     	if(this.isEmpty() || c.isEmpty()){
>     		return false;
>     	}
>         beginChange();
>         boolean removed = false;
>         for (int i = size()-1; i>=0; i--) {
>             if (c.contains(get(i))) {
>                 remove(i);
>                 removed = true;
>             }
>         }
>         endChange();
>         return removed;
>     }
> 
>     @Override
>     public boolean retainAll(Collection<?> c) {
>     	if(this.isEmpty() || c.isEmpty()){
>     		return false;
>     	}
>         beginChange();
>         boolean retained = false;
>         for (int i = size()-1; i>=0; i--) {
>             if (!c.contains(get(i))) {
>                 remove(i);
>                 retained = true;
>             }
>         }
>         endChange();
>         return retained;
>     }

@yososs Please file a new JBS issue for this. You will need to prove that your proposed change is functionally equivalent (or that any perceived changes are incidental and still conform to the spec). You should also think about whether your proposed change needs additional tests.

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

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