On Fri, 17 Apr 2020 10:22:15 GMT, John Hendrikx <jhendr...@openjdk.org> wrote:
>> @hjohn Thanks for looking into this. It looks like your changes do improve >> the issue with the JavaFX thread being >> swamped with listener de-registrations. Looking at the JavaFX thread in >> VisualVM, the removeListener call has dropped >> off the hotspots in the same way it did with my pull request. I wasn't >> fully confident of making changes to the Node >> hierarchy to remove listeners hence why I approached the issue from the >> other direction i.e. the obvious bottleneck >> which was the listener de-registration slowness. I do worry however that >> any changes down the road which add listeners >> to the Node hierarchy again without fully understanding the implications >> would lead us to the same point we are now >> where the slowness of listener de-registrations becomes an issue again. >> There are no tests that catch this scenario. I >> feel that ideally both solutions are needed but am happy to bow to the more >> experienced OpenJFX devs opinions here as I >> know my changes may be more fundamental and hence risky. > > The problem is that there are usually many nodes, but only very few scenes > and windows, so registering a listener for > each node on a scene or window is pretty bad design (also consider the amount > of notifications that a scene change > would trigger in such scenarios). As far as I can see, this is the only such > listener and only needed for two very > limited cases, and its addition in the past may have slipped through the > cracks. Adding a performance unit test that > specifically checks add/remove performance of nodes may prevent such future > regressions. @hjohn, agreed regards the issues of adding a listener to each node. Would it be worth doing the additional work of updating PopupWindow and ProgressIndicatorSkin to add their own listeners to make this a pull request that can be reviewed officially? I await any further comments from @kevinrushforth et al. ------------- PR: https://git.openjdk.java.net/jfx/pull/108
