Performance issue while listing statements of an inferred model

Question

I am developing an application using Apache Jena to work with RDF triples and OWL ontologies.

The problem

What I am currently trying to do is to get a model from a TDB triplestore, to infer on this model and to find some statements in the inferred model. This is done thanks to the StmtIterator listStatements(Resource s, Property p, RDFNode o) method. And then a really simple while(iter.hasNext()) loop is made to iterate over the statements.

At first glance, it seems to work well but it is really slow. For my reasonably small model, it takes approximately 5 minutes while it takes only a few milliseconds on the (not inferred) model.

An example with the Pizza ontology

In this example, I am using the Pizza ontology available here. The code looks like :

public class TestInferedModel {

    private static final String INPUT_FILE_NAME = "path/to/file";
    private static final String URI = "http://www.co-ode.org/ontologies/pizza/pizza.owl#";

    private static final Logger logger = Logger.getLogger(TestInferedModel.class);

    public static void main(String[] args) {
        Model model = ModelFactory.createOntologyModel();
        model.read(INPUT_FILE_NAME);

        Reasoner reasoner = ReasonerRegistry.getOWLReasoner();   
        reasoner = reasoner.bindSchema(model);

        Model infmodel = ModelFactory.createInfModel(reasoner, model);

        logger.debug("Model size : " + model.size() + " and inferred model size : " + infmodel.size()); 
        // prints Model size : 2028 and inferred model size : 4881

        StmtIterator iter = infmodel.listStatements();
        while (iter.hasNext()) {  // <----- Performance issue seems to come from this line
            // Operations with the next statement
            Statement stmt = iter.nextStatement();
            logger.info(stmt);
        }

        model.close();
    }
}

Here, the model size is approximately two thousands triples while the inferred model is made of a bit less than five thousands triples. However, running the code above takes much more time than running the same piece of code after editing StmtIterator iter = infmodel.listStatements(); to StmtIterator iter = model.listStatements();. Plus, when trying to add parameters to restrict the statements, the program seems to be running in an infinite loop.

I tried to add a couple of logger.debug() message to see where the program is wasting so much time and it seems that the issue comes from the while(iter.hasNext()) line.

The question

I thought the listStatements() method is of polynomial (or linear) complexity, not exponential, isn't it ? Is it normal that it takes so much time for the inferred model ? How can I avoid that ?

I'd like to be able to list statements and to manipulate the inferred model without requiring the user to wait ten minutes for an answer...

This issue seems similar to this one. However the answer is not really helping me to understand.

Performance issue while listing statements of an inferred model

0 Answers0