RFR: 6507038: Memory Leak in JTree / BasicTreeUI

[Alexey Ivanov]

On Tue, 23 Jan 2024 04:58:00 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

>> src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTreeUI.java line 1338:
>> 
>>> 1336:         if(rendererPane != null) {
>>> 1337:             if (!tree.isVisible()) {
>>> 1338:                 rendererPane.removeAll();
>> 
>> Wouldn't it be enough to remove `rendererPane` from and assign `null` to it?
>> 
>> It's done this way in `BasicTableUI` and `BasicListUI`:
>> https://github.com/openjdk/jdk/blob/0d8543d6773a516dad54038070dce507179d0709/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTableUI.java#L1656-L1658
>> and
>> https://github.com/openjdk/jdk/blob/0d8543d6773a516dad54038070dce507179d0709/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicListUI.java#L986-L988
>
> It is already been done in `completeUIUninstall` called from `uninstallUI`
> `rendererPane.removeAll `is done to remove all components that are added in `getNodeDImensions` which gets removed in `paint` but if tree is not visible, then `paint `is not called so those components are not removed, which I am trying to do now in `uninstallUI `by checking tree visibility condition

Okay, I see it. Then the added lines in `uninstallComponents` aren't needed because `rendererPane` is assigned `null` in `completeUIUninstall` which is called right after `uninstallComponents`, therefore `rendererPane` itself and all the components added into it are eligible for garbage collection.

Where is the memory leak then?

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PR Review Comment: https://git.openjdk.org/jdk/pull/17458#discussion_r1463114166