<Swing Dev> [10] RFR JDK-8175968: The javax.swing.filechooser.FileSystemView constructor consumes memory by adding a PropertyChangeListener that is never removed.

[Prasanta Sadhukhan]

On 7/7/2017 12:51 PM, Robin Stevens wrote:
> I still do not think you need a public dispose method.
> If you use the weak listener (the correct implementation), the 
> FileSystemView instance can be GC-ed, even when the 
> PropertyChangeListener is still attached to the UIManager.
>
> What you can do is:
> - Store a reference to the PropertyChangeListener in the 
> FileSystemView class as a field.
> - Override the finalize method of the FileSystemView class to 
> de-register the PropertyChangeListener from the UIManager. Thanks to 
> the weak listener, the FileSystemView will get GC-ed as the listener 
> no longer keeps a hard reference to it.
>
finalize() is deprecated from jdk9 and spec says
http://hg.openjdk.java.net/jdk9/client/jdk/file/80acf577b7d0/src/java.base/share/classes/java/lang/Object.java#l599

Classes whose instances hold non-heap resources should provide a method
* to enable explicit release of those resources, Regards Prasanta

> Not the nicest way to do such cleanup (which should probably happen on 
> the EDT) in a finalizer, but imho it still beats adding an extra 
> method to the API and shifting the burden to the API user.
>
> Robin
>
> On Thu, Jul 6, 2017 at 3:15 PM, Prasanta Sadhukhan 
> <prasanta.sadhukhan at oracle.com <mailto:prasanta.sadhukhan at oracle.com>> 
> wrote:
>
>     Hi Sergey,
>
>     I tried with the proposed WeakPropertyChangeListener but as far I
>     understand & tested, it seems also to rely on propertyChange() API
>     to be called, so the scenario mentioned in the bug will still fail.
>     I cannot find any other way rather than calling dispose() for the
>     scenario mentioned there.
>
>     Regards
>     Prasanta
>
>     On 7/5/2017 4:35 AM, Sergey Bylokhov wrote:
>
>         Hi, Prasanta.
>         Probably it is possible to implement it without users
>         interaction and new api?
>
>         ----- prasanta.sadhukhan at oracle.com
>         <mailto:prasanta.sadhukhan at oracle.com> wrote:
>
>             Hi All,
>
>             Please review a fix for a memory leak issue where
>             PropertyChangeListener
>             object added by FileSystemView constructor is never removed.
>             Proposed fix is to add dispose() method to be called by
>             app when they
>
>             want to remove this resource.
>
>             Bug: https://bugs.openjdk.java.net/browse/JDK-8175968
>             <https://bugs.openjdk.java.net/browse/JDK-8175968>
>             webrev:
>             http://cr.openjdk.java.net/~psadhukhan/8175968/webrev.00/
>             <http://cr.openjdk.java.net/%7Epsadhukhan/8175968/webrev.00/>
>
>             Regards
>             Prasanta
>
>
>

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