[mapguide-users] GDAL -- Failed to stylize layer... Cannot create any more connections to the OSGeo.Gdal FDO provider

[Pascal Coulon]

Dear All,

I have run a series of stress test on raster layers, using a URL of the
following sort:
http://10.XXX.XX.71/mapguide/mapagent/mapagent.fcgi?OPERATION=GETMAPIMAGE&VERSION=1.0.0&MAPNAME=Browser_Default&LOCALE=EN&MAPDEFINITION=Library://PILOT_TEST/Maps/MainMap.MapDefinition&FORMAT=PNG&SETVIEWCENTERX=190722&SETVIEWCENTERY=205644&SETVIEWSCALE=8600&SETDISPLAYDPI=78&SETDISPLAYWIDTH=600&SETDISPLAYHEIGHT=600&USERNAME=Administrator&PASSWORD=XXXX. 
The idea was to test the actual MapGuide server rather than any application
using the underlying map server. I have gradually increased the number of
concurent users on various raster layers. I got some excellent results on
most of the raster layers. However, on one specific rather layer (UK
Ordnance Survey Aerial Images - 8.6GB), the system started to crash with
only two concurent users.  http://www.nabble.com/file/p16823109/Error.log
Error.log On inpestecting the error log (see attached file), I noticed the
following error being logged: 

Error: Failed to stylize layer: OS_AerialPhotography_SN
        Cannot create any more connections to the OSGeo.Gdal FDO provider.

I had created a raster catalogue
(http://trac.osgeo.org/fdo/wiki/FdoGdalNotes); which had help on the smaller
rater dataset. But for this larger dataset, I did not get any benefit. 

I understand that the GDLA library is single threaded. This means that if
too many requests are queue in the stak, it might eventually time out and
then through the above error. However, this error seemed to be logged before
any set time out. 

For completness, here is the following plateform specifications:

OS: Windows 2003 Server SP2
CPU: 2.20 GH
RAM: 3.62GB
MGOS 1.2

Would an upgrade to MGOS 2.0 provides any benefits? 
Can anyobody suggest a way for handling very large raster dataset?

Any help would be much apprecaited.

Pascal  


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