RFR: 6507038: Memory Leak in JTree / BasicTreeUI [v8]

[Harshitha Onkar]

On Thu, 1 Feb 2024 03:16:27 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..
>
> Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Test updated

test/jdk/javax/swing/plaf/basic/BasicTreeUI/TreeCellRendererLeakTest.java line 30:

> 28:  * @summary Verifies memory leak in BasicTreeUI TreeCellRenderer
> 29:  * @run main TreeCellRendererLeakTest
> 30:  */

jtreg header can be moved  to _before class declaration_ location.

test/jdk/javax/swing/plaf/basic/BasicTreeUI/TreeCellRendererLeakTest.java line 111:

> 109:     }
> 110: 
> 111:     // <editor-fold defaultstate="collapsed" desc=" Generated Code ">

Editor Code Folding can be removed to avoid this code being collapsed in IDE.

test/jdk/javax/swing/plaf/basic/BasicTreeUI/TreeCellRendererLeakTest.java line 117:

> 115:         jScrollPane1 = new javax.swing.JScrollPane();
> 116:         jTree1 = new javax.swing.JTree();
> 117:         jPanel2 = new javax.swing.JPanel();

Fully qualified class name are redundant here since we already have the required imports.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17458#discussion_r1480676447
PR Review Comment: https://git.openjdk.org/jdk/pull/17458#discussion_r1480700180
PR Review Comment: https://git.openjdk.org/jdk/pull/17458#discussion_r1480675309