Re: BufferedImages not garbage collected -- any suggestions?

• Subject: Re: BufferedImages not garbage collected -- any suggestions?
• From: Doug Zwick <email@hidden>
• Date: Thu, 30 Mar 2006 10:44:44 -0700
• Delivered-to: email@hidden
• Delivered-to: email@hidden

Michael Ellis wrote:

when I check the type of the returned objects in the debugger, I find
that I am receiving "apple.awt.OSXImage" instances, not the
BufferedImage instances I expected.  I then wrote a little test
program, and I found that "apple.awt.OSXImage" instances are returned
by the java.awt.Toolkit.createImage() method.

So, perhaps we have an explanation here.  I've found that flush()ing
my images made a big difference in my program's ability to reclaim
memory, but, as we thought we were using BufferedImages, we were
unable to determine why this action would matter for that particular
java.awt.Image variant.  In fact, it would seem that this  library
method I am using is not returning the promised BufferedImage, but
instead a different Image subclass.  Hence, the flush() method is
useful for the actual instance returned.

I suppose the lesson learned here is that if you only know you're
going to acquire some generic java.awt.Image subclass, go ahead and
make arrangements to flush() it.

I would still think it reasonable to expect an OSXImage to clean
up after itself automatically. However, OSXImage does not implement
flush -- that is done by its base class, sun.awt.image.ToolkitImage.
ToolkitImage does not implement finalize. I think Apple could fix
the problem by implementing finalize in OSXImage, and having it call
flush (before calling super.flush). I cannot see any way to detect
when an Object is about to be collected via an external mechanism
(e.g. a listener, Reference object, etc.), so we can't hack in a fix
externally, it needs to be built in to the ToolkitImage class tree.

We have seen the flush issue on other platforms than OS X, so I think
the "proper" fix needs to be put in by Sun, by implementing finalize
on ToolkitImage to force a flush before GC reclaims the image. Has
anyone reported this to Sun?
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Java-dev mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/java-dev/email@hidden

• Prev by Date: Re: Using Java 1.3 on PowerPC and 1.5 on Intel
• Next by Date: Re: Using Java 1.3 on PowerPC and 1.5 on Intel
• Previous by thread: Re: BufferedImages not garbage collected -- any suggestions?
• Next by thread: Re: BufferedImages not garbage collected -- any suggestions?
• Index(es):
  • Date
  • Thread