[OpenJDK 2D-Dev] [PATCH] 4494651: Wrong width and height in BufferedImage GraphicsConfiguration objects

[Torsten Landschoff]

Hi Dmitri, 

On Tue, Feb 17, 2009 at 06:13:47PM -0800, Dmitri Trembovetski wrote:
>
>   Note that this fix may have some performance
>   implications for cases when there are caches based on the
>   graphics configuration of the Graphics object used for
>   rendering - these caches may grow uncontrollably.

I don't see how this could happen with either of my patches:

a) The trivial approach will create a new GraphicsConfiguration instance on
each call to Graphics2D#getDeviceConfiguration. Which I would expect as the
JavaDoc states that it "Returns the device configuration associated with this
Graphics2D.". Reference:
http://java.sun.com/javase/6/docs/api/java/awt/Graphics2D.html#getDeviceConfiguration()

b) My second patch uses a WeakHashMap to cache the already retrieved 
graphics configuration instances. I would expect it to be faster for very few
instances cached and slower when many instances are cached. So I don't think
it's worth the effort.
Anyway, assuming that the WeakHashMap will clean up left-over keys, this 
implementation should keep at most as many graphics configuration instances
as there are Graphics2D instances referring to BufferedImages, for which 
getDeviceConfiguration was called.

What am I missing?

>   I don't know of any other solution for this bug, but I'm
>   not sure fixing it would do more harm than good.
>   The bug has only 3 votes after 8 years (all of them
>   in 2001-2002)..

Is it better to leave a known bug unfixed for fears of performance 
regressions? While this bug goes unnoticed for long time, actually
finding it (even though it is recorded) can consume a lot of 
developer time.

Greetings, Torsten