Re: [OpenMap Users] OMGraphicHandler Layer and high CPU usage

From: Sean King <>
Date: Tue, 28 Jun 2005 14:18:54 -0400

Sorry for a late response but I set the enviroment variable J2D_PIXMAPS
and used the jvm parameter you supplied and we are currently down to 3
percent cpu w/ the X server process now. Thanks for the help. I will
probably bug everyone later:)

Sean King
Rob Ratcliff wrote:
> We've had to deal with this as well in the past. Here are a few things 
> you can try::
> 1.) Set the render policy of especially any layers that draw lots of 
> lines (like the VPF layer) to BufferedImageRenderPolicy
> (This has a huge impact on the X Server performance.)
> 2.) try changing these settings:
> setenv J2D_PIXMAPS server|shared
> java -Dsun.java2d.pmoffscreen=false|trure
> 3.) Create a timer that calls repaint on the layers every n seconds 
> rather than repainting every time there is a change.
> 4.) Create an image buffer (an extension of buffered map bean) that 
> paints all layers that don't change except during projection changes.
> 5.) Track the dirty region of the map and call repaint specifying the 
> dirty rectangle.
> Hope that helps!
> Rob
> King, Sean wrote:
>> I have recently have taken over some map development for a project 
>> that keeps track of objects moving around on a map. There are 
>> multiple dynamic layers that need to be updated continuously (say 
>> once a second) on a detailed terrain. Currently the layers are being 
>> repainted every second. This appears work fine in Windows but in 
>> Linux I am experiencing the high levels of CPU usage on the X Server 
>> process which make map functionality slow. It seems the cause of the 
>> high level of X usage is because of the repaints to the 
>> OMGraphicHandlerLayers. Zooming in and out on the map also causes 
>> high CPU usage w/ the X server but I am sure this stems from the same 
>> repaint problems. Zooming in the OpenMap demo doesn’t cause high CPU 
>> usage so I am sure the fault lies w/in our code.
>> My question is, has anybody experience similar problems in Linux 
>> before and does anybody have some insight on how to fix this problem? 
>> Currently, all the layers are calling repaint(). Should I just call 
>> repaint(x,y,h,w) on the moving objects w/in the layer.
>> Sean King
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Received on Tue Jun 28 2005 - 14:21:18 EDT

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