I have spent a good portion of today profiling uDig and found
something strange. As one adds and remove layers the Heap Size keeps
growing and growing and growing. However if the garbage collector is
ran the heap size goes right back down. It seems that it is the byte
arrays in the BufferedImages that are taking a while to clear up.
Perhaps if I pool them better rather than always recreating them it
will help the heap problem. But it seems to me that the Garbage
collector should kick in before a heap space error occurs. ( I
haven't been able to reproduce the heap space error yet... I've
added and removed 10 shapefile layers probably 30 times without
problems. And I have the heap space set to the default Java size.
I have tested on both windows and OSX. I did the profiling on OSX
but the performance seemed even better on Windows (shock!).
What is your configuration? Are there any other variable that I can
look at?
Jesse
On 7-Dec-06, at 6:05 AM, Jesse Eichar wrote:
Thanks Michael, I will look in to the problem and will get back to
you this evening on what I found.
Jesse
On 7-Dec-06, at 12:26 AM, Schneider, Michael wrote:
Jesse, thanks for the answers.
Sure, it's better to use one large shapefile instead of several
smaller ones. I tried that after detecting the heap space problem
with the gif files.
I think it is not the maximal amount of memory which causes the
problem, but perhaps a memory leak or memory fragmentation: Even
when adding and removing only one single layer I detect that
problem after having added and removed a layer more than 30 times.
Michael
Von: [EMAIL PROTECTED] [mailto:udig-devel-
[EMAIL PROTECTED] Im Auftrag von Jesse Eichar
Gesendet: Mittwoch, 6. Dezember 2006 18:13
An: User-friendly Desktop Internet GIS
Betreff: Re: AW: [udig-devel] Heap space error adding/removing
graphical layers
Hi,
There is a limitation to the number of layers that can be
realistically added because currently each layer has a buffer that
it writes to that is the size of the screen and is in 32-bit
colour. Obviously a good chunk of memory especially when the
screen is large. So it is better to have large shapefiles than
many shapefiles because the Shapefile renderer is highly optimized
for large shapefiles and performance will be much better rendering
a 1 GB shapefile than 100 100KB shapefiles.
This decision was part of the design because it allows some fun
optimizations (for example enabling and disabling layers) but as
of 1.1.1 we will have an "intelligent" system that will set a
maximum number of buffers depending on the memory size so that
this issue will no longer be a problem.
Jesse
On 6-Dec-06, at 3:54 AM, Schneider, Michael wrote:
Is grid coverage also involved when the layers are created from
shapefiles?
Using a bunch of shapefile layers instead of the GIF layers I
also ran into the same heap space error after adding and removing
the layers several times. (Each shapefile only had one single
feature, a point in this case.)
Michael
Von: [EMAIL PROTECTED] [mailto:udig-devel-
[EMAIL PROTECTED] Im Auftrag von Jesse Eichar
Gesendet: Dienstag, 5. Dezember 2006 18:47
An: User-friendly Desktop Internet GIS
Betreff: Re: [udig-devel] Heap space error adding/removing
graphical layers
Hi
There are 2 main possibilities that I can think of.
1. Make sure that you are passing in a heap space parameter to
your application or increase it if you already are. For example
-Xmx512M will assign 512 MB of memory to the heap space of the
JVM. That should help with the problem.
2. GridCoverage support is less than perfect at the moment
(although Jody is playing with a new version that shows promise)
and takes much more memory than it should. So it is likely that
the World+Image is what is causing problems. I'm not totally
sure what can be done about this. But if it is causing problems
then perhaps some memory optimizations can be made.
Jesse
On 5-Dec-06, at 3:33 AM, Schneider, Michael wrote:
Hello,
using uDIG RC 5 I got a heap space error after adding several
layers. Each layer was created from a very small graphic (png or
gif file of less than 1 KB) together with a world file. The same
was true when each layer was created from a small shapefile.
The intension is as follows: The user creates a list of
locations and these locations are shown on a map. When creating
a new list of locations, the old locations are removed from the
map and the new ones are displayed.
I did it similar to the descriptions in the FAQ "How do I create
a map programmatically" and "I want to add an image to the map,
how do I do that?"
I created a map using createCreateMapCommand
I added about ten layers (see above what the layers looked like)
with either createAddManyLayersCommand (all layers together) or
createAddLayerCommand (one layer at a time)
When a new list was created I removed the old layers using
createDeleteLayer command, set the new bounding box with
createSetViewportBBoxCommand and added the new layers to the map.
After doing these several times I run into the heap space error.
I also get this error when I only add and remove one layer (i.e.
location lists with only one entry), but it takes longer to get
the error.
I also tried it "the old way" with MapFactory.processURLs - with
a similar result: The error appeared as well, but it took longer
to get it.
Am I doing it the wrong way? Is there a better way?
I also wanted to try RC 6a. Are there any changes related to the
layers view and showing the map? In RC 5 after adding the layer
to the map they were displayed at once. In RC 6a I can see them
in the catalog and in the project window, but they do not appear
in the layers view automatically and are not displayed. I'll
have a closer look to that to see whether I get the heap space
error in RC 6a as well.
Michael
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel
