Thomas E Deweese wrote:
> Ok as I thought you are definitely beeing called from multiple
> threads (as you admit later :).
Yes there are multiple threads in my program, but my graphics code is
only being called by one thread. I tried printing the SVGGraphics2D
and thread name as you suggested, and there's only one thread
(originated by the servlet's doGet()) manipulating the SVGGraphics2D.
> GA> // my pre-existing SVGGraphics2D, that I wish to paint on
> GA> SVGGraphics2D g = ...;
>
> I assume by this you mean it is some sort of singleton or shared
> instance (from a static or some such)?
No not static or shared, but rather dynamically created for each
doGet().
> GA> // create a copy of this SVG SVGGraphics2D g2 =
> GA> (SVGGraphics2D) g.create();
>
> Be aware that this does not appear to do a deep copy , and this
> method is not thread safe (so if two threads call g.create() at the
> same time you will be in trouble).
To be honest I'm not sure why the create() is needed; I'm just
mimicking what's being done in SwingSVGPrettyPrint. I'd love to hear
an explanation from the author of what that's all about. But as I
said before, it's always the same thread calling the create().
> Have you tried putting the above code in a synchronize block on g?
Yes, and I still get ArrayIndexOutOfBoundsException.
> GA> Actually it's being called from a Servlet so there are certainly
> GA> multiple threads in play, but a new SVGGraphics2D is created for
> GA> each doPost/doGet, and I do all my painting serially from that
> GA> thread. I'm not doing any painting in response to GUI/Swing
> GA> events.
>
> When you say a new SVGGraphics2D is created for each one are you
> counting 'create' as creating a new one? If so this is the problem.
No. I'm doing the following for each doGet():
DOMImplementation impl =
SVGDOMImplementation.getDOMImplementation();
Document doc = impl.createDocument(svgNS, "svg", null);
g = new SVGGraphics2D(doc);
(Perhaps the DOMImplementation should be cached...)
Thanks again for your help in debugging this.
--
George Armhold
Rutgers University
Bioinformatics Initiative
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