<AWT Dev> Memory leaks due to static references in AWT & Swing

Oleg Sukhodolsky son.two at gmail.com
Thu Jul 21 04:59:09 PDT 2011

On Wed, Jul 20, 2011 at 12:43 PM, Roman Kennke <roman at kennke.org> wrote:
> Hi Oleg,
>> as far as I can see you suggest to replace strong references to
>> focusOwner, permanentFocusOwner, focusedWindow, and activeWindow to
>> weak ones.
>> But do you have test which can prove that any of these fields cause
>> real memory leak?
>> As far as I know KFM is supposed to update these fields as soon as
>> focus state has been changed, thus if
>> you do have memory leak then it is a bug in KFM and your fix is just a
>> workaround for the problem.
> That is a reasonable concern.
> What I know is that in one of the projects at my workplace we *are*
> having problems with the KFM keeping the permenentFocusOwner even though
> it should be GCed. I have no testcase though.
> The permanentFocusOwner seems to be reset only from removeNotify(), so I
> guess the question is, could a component hierarchy go out of scope (in a
> valid way) without having removeNotify() being called?

as far as I know, it should not (but we always may have some
"inventive" program or bugs ;)

> On the other hand, I would still like to understand why are those fields
> static? Shouldn't they be instance in the KFM?

KFM can be set by user and it is local to app context. Of course it
would be better to have these fields non-static, but
current implementation depends on this and someone will need to change
significant amount of fragile code to do this.


> Regards, Roman

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