Mapviewer performance problem using image format FORMAT_RAW_COMPRESSED

Question

I am using the MapViewer.FORMAT_RAW_COMPRESSED map image in my (java) map application because some features must be clickable and as far as I can work out, this is the only way to achieve this in a Java client. On my local system, running the map server in an oc4j container, this works about as fast as using FORMAT_GIF_URL and loading the image from this url. There also doesn't seem to be much difference in memory and cpu usage.
When I direct the request to a map server running on a remote Application Server the rendering time grows exponentially. The same maprequest using FORMAT_GIF_URL runs as fast as it does in my local OC4J container. The problem seems to be in "packing time" in RealWorker:
Remote AS:
Thu Jun 30 13:59:34 CEST 2005 DEBUG [oracle.lbs.mapserver.core.MapperPool] freeMapper() begins...
Thu Jun 30 13:59:34 CEST 2005 DEBUG [oracle.lbs.mapserver.core.RealWorker] [RealWorker] preparation time: 99ms
Thu Jun 30 13:59:34 CEST 2005 DEBUG [oracle.lbs.mapserver.core.RealWorker] [RealWorker] querying/rendering time: 5560ms
Thu Jun 30 13:59:34 CEST 2005 DEBUG [oracle.lbs.mapserver.core.RealWorker] [RealWorker] packing time: 142605ms
Thu Jun 30 13:59:34 CEST 2005 DEBUG [oracle.lbs.mapserver.core.RealWorker] [RealWorker] --------------- total time: 148264ms
Local OC4J:
Thu Jun 30 15:34:42 CEST 2005 DEBUG [oracle.lbs.mapserver.core.MapperPool] freeMapper() begins...
Thu Jun 30 15:34:42 CEST 2005 DEBUG [oracle.lbs.mapserver.core.RealWorker] [RealWorker] preparation time: 540ms
Thu Jun 30 15:34:42 CEST 2005 DEBUG [oracle.lbs.mapserver.core.RealWorker] [RealWorker] querying/rendering time: 2490ms
Thu Jun 30 15:34:42 CEST 2005 DEBUG [oracle.lbs.mapserver.core.RealWorker] [RealWorker] packing time: 120ms
Thu Jun 30 15:34:42 CEST 2005 DEBUG [oracle.lbs.mapserver.core.RealWorker] [RealWorker] --------------- total time: 3150
The test server is smaller than my local system and more applications are running on the AS, generating the map takes all the available memory and cpu, but the difference between the time it takes generating a GIF image and generating a Java image of almost a factor 50 is puzzling.
What could cause this enormous difference? Any idea's about how we can analyze or solve this? What could RealWorker be doing in this packing time? Any hints would be greatly appreciated.
Many thanks,
Ida

Answer 1

Thanks for the replies!
1. Which AS version are you using? -> 10.1.2
2. Just as a test, if you restart AS (if possible) do you still get the same values? -> yes, we restarted the AS and the results are the same.
The server is indeed running low in memory. It is a 512MB machine, just big enough to run the AS. The production server will have some more, but not very much. Could I estimate how much extra memory it will need to keep a good performance when generating maps with live features? And maybe I'm wrong, but shouldn't the extra load for the java image only be on the client, since that's where the image is made? On the server it's just the image data, isn't it?
I tried removing the basemap, but that reduces the loading time just with a few seconds. The live themes are jdbc themes and result in only some 20 to 30 geofeatures. Removing them from the request so only an empty image with a title is retrieved still takes about 117 seconds. Reducing the device size does reduce the loading time, so it does seem to have something to do with the amount of pixels in the image space, not with the data. Could it be that in the "packing" of the image something happens that takes a lot of memory, related to the amount of pixels?
In my situation it would be handy if the live features were also returned when the image format is not set to FORMAT_RAW_COMPRESSED, it is also possible to draw shapes onto an existing image and this would bypass the memory problems.
Thanks for any further help.
Ida