[Geotools-devel] Issues with System.loadlibrary

[Pierre M. <pie...@ca...>]

Hi list,

I recently proposed a pull-request on geotools[1] and imageio-ext[2], which
aims to limit the number of System.loadLibrary() concerning the GDAL native
lib, and maybe I should have asked here before posting them, so excuse me
if do things in the wrong order ;-)

The main motivation about this proposal is that we encountered issues when
several webapps were trying to make use of the same native library in the
same tomcat container. While digging in the issue, I noticed in the tomcat
logs that even if it was correctly configured to be able to resolve the
native lib path, it refused to load GDAL more than once (any further
initializations of the GDAL bindings were causing a "UnsatisfiedLinkError:
Native library <lib> already loaded in another classloader", then only the
first initialized webapp could use JNI GDAL/OGR bindings).

Willing to fix the issue, I developed a sample webapp that I duplicated 2
times in the same tomcat environment, ensuring that 1. the bindings were
available while calling them directly, and enumerating GDAL and OGR
drivers, 2. they were also available using GeoTools related classes (which
basically were doing the same thing as previously), and it worked.

My point of view on the problem is that the gdal.jar bindings should be
shared across the webapps (using CATALINA_HOME/lib for instance) instead of
being packaged into each ones, and that the loadlibrary should be done at a
higher level of classloading (i.e. ensuring that no jars bundled into the
webapps would call System.loadLibrary by themselves), anyway I'd like to
get some comments about it, maybe I'm wrong and this is not the way to fix
the issue, and maybe it is already done this way for a particular reason
I'm not aware of.

So what do you think about it ? I'd be glad to have some feedbacks on this.

Best regards, and thanks,

[1] https://github.com/geotools/geotools/pull/443

[2] https://github.com/geosolutions-it/imageio-ext/pull/76
-- 

Pierre Mauduit

Ingénieur développement

Camptocamp France SAS

Savoie Technolac, BP 352

73377 Le Bourget du Lac, Cedex

Tel (France) : +33 4 79 26 58 02

Fax : 04 79 70 15 81

Mail : pie...@ca... <yve...@ca...>

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