java - Why can't I instantiate DataImportHandler in Solr on JBoss?

Question

I'm trying to set up Solr 3.5.0 on JBoss 5.1. Everything works quite fine. I copied war into deploy dir, all the dependencies from dist and contrib directories into the lib (or earlier deploy) directory.

I can start a server, everything works fine, but whenever I want to activate the DataImportHandler to index data in my DB, I get an error.

Basically what I do is I copy is I copy a core from example/example-DIH/solr/db (Or whole example, that doesn't matter), I register the core in solr.xml and at startup I get an error:

15:17:10,707 SEVERE [RequestHandlers] org.apache.solr.common.SolrException: Error Instantiating Request Handler, org.apache.solr.handler.dataimport.DataImportHandler is not a org.apache.solr.request.SolrRequestHandler
at org.apache.solr.core.SolrCore.createInstance(SolrCore.java:427)
at org.apache.solr.core.SolrCore.createRequestHandler(SolrCore.java:461)
at org.apache.solr.core.RequestHandlers.initHandlersFromConfig(RequestHandlers.java:157)

I'm pretty sure my request handler definition is correct, but just to be sure:

<requestHandler name="/dataimport" class="org.apache.solr.handler.dataimport.DataImportHandler">
<lst name="defaults">
  <str name="config">dataimport.xml</str>
</lst>

As far as I can find, this error may be caused by DataImportHandler and SolrRequestHandler supposedly being hold different class loaders.

Whenever I start a Solr from the start.jar app in example (I think it starts a Jetty server) it works fine.

My question is: is this really because of the class loader issue, or some other thing? And, more importantly: how do I fix it?

Answer 1

This is a class loader issue and according to this post on the Lucene Developer Mailing List you need to do the following:

make sure that the dataimport jars are NOT in the classpath and not loaded by other classloaders but from the path specified in solrconfig.xml. This will ensure that the dataimport classes are loaded by the same classloader.

Please see the thread for more details.