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Swing and AWT memory leaks



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Swing and AWT memory leaks

Posted by Adrian Dickin on 23 Feb 1999, 6:52 AM

We've had problems with memory leaks and tracked all of ours down using
OptimizeIt. Some of the problems were due to bugs/problems within AWT
and Swing.

We had a main screen that added panels using GridBagLayout. The
problem here was that internally GridBagLayout uses a HashTable.
When a panel was removed it wasn't removed from the hash table,
so it would never be GC. In bug parade this is Bug Id 4170095
and was fixed 1999-02-01.

These hang around because they register for keystrokes,
within BasicToggleButtonUI, and so their parents etc. are never
We fixed it by calling resetKeyboardActions() on every
JCheckBox/JRadioButton. In bug parade this is Bug Id 4129207
and is still in progress.


> I have observed that AWT and Swing components that are added
> to a top-level component never gets garbage collected as long
> as the top-level component exists(i.e. not been made null).

> We have developed an MDI application using Swing.This app
> contains child windows(JInternalFrames) and dialogs(which are
> also designed as JInternalFrames).Upon bringing such JInternalFrames
> 15-20 times in a 64MB system(WIN - 95) the Application throws
> OutOfMemoryError.And after sometime the whole app goes for a toss.
> I believe the JVM before throwing an OutOfMemoryError should run the
> GC and any unreferenced object on the heap should be GC'ed.Let me
> tell you here that our reference to these JInternalFrames are made
> null after these windows are closed.

> I suspect some of the AWT & Swing classes might be keeping
> reference to this objects which they never seem to release.
> I would request you all to reply soon if you have any idea
> why this is happening? If u want I can provide you with test codes.

> Thanks in advance

> Pradeep


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