[mapguide-internals] fdogdal, ECW, etc

[Bruce Dechant]

Frank,

The error you are seeing " Cannot create any more connections to the
OSGeo.Gdal FDO provider." is a result of trying to create more than one
concurrent connection to the GDAL provider.
Since the GDAL provider is single threaded only 1 thread of the server
is allowed to use the GDAL provider until it releases it. The other
threads that want to use the single threaded provider are blocked for up
to 60 seconds. If they cannot get an exclusive lock on the provider in
this window of time then they will throw this exception. You can
sometimes run into this issue if you forget to close a reader and
therefore the server doesn't know you are actually done with the
provider until eventually the connection becomes old and is removed from
the cache.

The amount of debugging information is something we could improve upon.

Thanks,
Bruce




-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Frank
Warmerdam (External)
Sent: May 9, 2007 10:57 PM
To: MapGuide Internals Mail List
Subject: [mapguide-internals] fdogdal, ECW, etc

Folks,

OK, I spent part of the afternoon and evening trying to build and test
fdogdal with ecw/mrsid support (and the remainder of the afternoon
evening trying to rebuild my ego after failure).

I went through a few different scenarios with varying issues.  But
ultimately this report captures the normal failure with my own build
of fdogdal, and gdal13.dll

----
C:\Program Files\MapGuideOpenSource\Server\Bin>mgserver /run
Running the server interactively as an application instead of as a
service.

(3648|5444) Server starting...
(3648|5444) PROJ4 Coordinate System Library
(3648|5444) Server started.
GDAL: Auto register C:\Program
Files\MapGuideOpenSource\Server\Bin\gdalplugins\g
dal_ECW.dll using GDALRegister_ECW.
ECW: Actually creating ECW driver.
ECW: OpenECW(C:/temp/ecw/World.ecw)
ECW: Open(C:/temp/ecw/World.ecw)
ECW: NCScbmOpenFileView(C:/temp/ecw/World.ecw): eErr = 0
ECW: FileInfo: SizeXY=4320,2153 Bands=3
        OriginXY=-180.084,89.75  CellIncrementXY=0.083333,-0.083333

ECW: projection=RAW, datum=RAW
GDAL: GDALOpen(C:/temp/ecw/World.ecw) succeeds as ECW.

(3648|5464) Cannot create any more connections to the OSGeo.Gdal FDO
provider.
Exception occured in method MgFdoConnectionManager.Open at line 257 in
file c:\b
uild_bond_area\mapguide_open_source_v1.2\build_11.8\mgdev\server\src\com
mon\mana
ger\FdoConnectionManager.cpp
----

In this scenario ran MgServer with the CPL_DEBUG environment variable
set to ON.  I also had to clear the GDAL_DRIVER_PATH environment
variable
but I suspect that was a local issue on my machine, not something that
will happen to everyone.

Can anyone comment on the error message reported by MgServer:

(3648|5464) Cannot create any more connections to the OSGeo.Gdal FDO
provider.
Exception occured in method MgFdoConnectionManager.Open at line 257 in
file 
c:\build_bond_area\mapguide_open_source_v1.2\build_11.8\mgdev\server\src
\common\mana
ger\FdoConnectionManager.cpp

This occured some time after selecting an ECW based raster layer (like
one
or two minutes later).

I was using WebStudio since I despaired of getting the Studio 2008 beta
downloaded and installed.  I don't have much capability to edit a map
configuration with raster data using webstudio, but existing
configurations
seem to work ok and I can edit the directory for a data source object.

I find it painfully difficult to find out what is happening in mapguide.
Is there anything a /debug switch for MgServer that will produce lots of
logging info on what is going on?

Best regards,
-- 
---------------------------------------+--------------------------------
------
I set the clouds in motion - turn up   | Frank Warmerdam,
warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo,
http://osgeo.org

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