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Thank you, Jesse, for your work and the informations.
That might be a hint for me to have a closer look
at.
When I detected the problem first, I was not using uDIG
as an RCP application but was using parts (plugins) of uDIG (seen from the
user's point of view only the map editor and the layers view) in another RPC
application.
But I repeated what I did with the "whole uDIG" as
an RPC application, and I could reproduce the error. Doing so I created a
command which added the layers (before it removed the old ones). This was
started from within Eclipse with no special settings set (except those being
part of the uDIG SDK). A plugin with this command was the only enhancement to
uDIG. I'm running on Windows XP Professional.
Cheers,
Michael
Von:
udig-devel-bounces@xxxxxxxxxxxxxxxxxxxxx
[mailto:udig-devel-bounces@xxxxxxxxxxxxxxxxxxxxx] Im Auftrag von Jesse
Eichar
Gesendet: Donnerstag, 7. Dezember 2006 23:44
An:
User-friendly Desktop Internet GIS
Betreff: Re: AW: AW: [udig-devel]
Heap space error adding/removing graphicallayers
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
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
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
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User-friendly Desktop Internet GIS (uDig)
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User-friendly Desktop Internet GIS (uDig)
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User-friendly Desktop Internet GIS (uDig)
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User-friendly Desktop Internet GIS (uDig)
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