On Thu, Jul 21, 2011 at 9:41 PM, Bertrand, Matt
<mbertr...@cga.harvard.edu> wrote:
> Hello,
> I am running a customized GeoNode instance (which I know complicates things)
> that has been exhibiting a serious but intermittent problem when a layer is
> added or removed in the GeoServer 2.1 catalog: many layers suddenly become
> inaccessible via WMS/WFS with NullPointerExceptions thrown in the log (see
> Exception #1 below). In the GeoServer admin interface, all layers still
> appear in the list, but each problematic layer's 'Edit' page throws a
> similar exception (see #2 below). Restarting geoserver's Tomcat container
> resolves the issue until it happens again. The problem has increased in
> frequency as the site's traffic has increased. Could this be a concurrency
> issue related to the catalog cache?
> Exception #1:
>
> 19 Jul 09:49:14 ERROR [wms.capabilities] - An error occurred trying to
> determine if the layer is geometryless
> java.lang.NullPointerException
> at
> org.geoserver.catalog.impl.DefaultCatalogFacade.getResource(DefaultCatalogFacade.java:288)
Never seen it, but I see how this could happen. The two blocks of relevant code:
public <T extends ResourceInfo> T getResource(String id, Class<T> clazz) {
List l = lookup(clazz, resources);
for (Iterator i = l.iterator(); i.hasNext();) {
ResourceInfo resource = (ResourceInfo) i.next();
if (id.equals(resource.getId())) {
return ModificationProxy.create((T) resource, clazz );
}
}
return null;
}
List lookup(Class clazz, MultiHashMap map) {
ArrayList result = new ArrayList();
for (Iterator k = map.keySet().iterator(); k.hasNext();) {
Class key = (Class) k.next();
if (clazz.isAssignableFrom(key)) {
result.addAll(map.getCollection(key));
}
}
return result;
}
The list returned by lookup will contain a null value if the map contents
are modified (entry removed I guess) while scanning over its contents.
A concurrent data structure should be used instead imho (probably
a combination of two concurrent structures, multimap cannot be replaced
with just one).
Or, alternatively, wrap everything with read/write locks
Cheers
Andrea
--
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Ing. Andrea Aime
GeoSolutions S.A.S.
Tech lead
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phone: +39 0584 962313
fax: +39 0584 962313
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