RFR: 6507038: Memory Leak in JTree / BasicTreeUI

[Harshitha Onkar]

On Wed, 17 Jan 2024 07:19:21 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

> When using a TreeCellRenterer which creates new components in getTreeCellRendererComponent() in a JTree that is not visible, changes to the nodes cause a memory leak.
> When a node is changed, the Method getNodeDimensions() is called to calculate the new dimensions for the node. In this method, getTreeCellRendererComponent() is called to obtain the renderer component (what else...) and [this component is added to rendererPane](https://github.com/openjdk/jdk/blob/36f4b34f1953af736706ec67192204727808bc6c/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTreeUI.java#L3283-L3284). It is not removed from the rendererPane afterwards. 
> Only when the tree is painted, the paint() method does a removeAll on the rendererPane [in this code](https://github.com/openjdk/jdk/blob/36f4b34f1953af736706ec67192204727808bc6c/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTreeUI.java#L1500)
> 
> FIx is added to remove the components from rendererPane when the JTree UI is changed/uninstalled only when tree is not visible since they are already removed when tree is painted in paint() method..

Ran the reproducer attached to JBS without and with the fix. The "Live Label count" seem to increase in both cases.
After running the test, I switched to tab 2, which makes tab 1 (with JTree) inactive but during this time the Live label count increase.
Will a test case be added as part of this fix? 


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PR Review: https://git.openjdk.org/jdk/pull/17458#pullrequestreview-1828473222