RDF4J只调度针对三层存储的5个查询

Question

我在处理语义数据技术方面还有一些问题:我有一个GraphDB Triplestor在我的机器上本地运行，试图使用RDF4J和Java对它调度一些SPARQL查询。从下面的代码中可以看到，将连续启动10个查询。然而，只有5 get启动(我看到0-4在控制台中)。问题似乎是，出于某种原因，我仅限于5个开放的HTTP连接。repConn.close()的任何调用似乎都不会改变任何事情。有人有什么想法吗？

import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.repository.RepositoryConnection;
import org.eclipse.rdf4j.repository.http.HTTPRepository;

public class testmain {

public HTTPRepository rep;
public RepositoryConnection repConn;

public static void main(String[] args) {

    testmain test = new testmain();

    test.rep = new HTTPRepository("http://localhost:7200/repositories/test01");

    //test.repConn = test.rep.getConnection();

    for (int i = 0; i < 10; i++) {

        test.repConn = test.rep.getConnection();
        String queryString = "select ?archiveID where { ?video <http://www.some.ns/ontology##hasArchiveID> ?archiveID .}";

        try {
            TupleQuery tupleQuery = test.repConn.prepareTupleQuery(QueryLanguage.SPARQL, queryString);
            TupleQueryResult queryResult = tupleQuery.evaluate();
        } finally {
            test.repConn.close();
        }

        System.out.println(i);

    }
}

}

Answer 1

您还需要关闭查询结果，否则repCon.close什么都不做。

try {
        TupleQuery tupleQuery = test.repConn.prepareTupleQuery(QueryLanguage.SPARQL, queryString);
        TupleQueryResult queryResult = tupleQuery.evaluate();
        queryResult.close(); // this should solve your issue

    }

或者更好地使用新的rdf4j流API(QueryResults.stream(gqr))。为你关闭一切。http://docs.rdf4j.org/migration/ (2.6.5点)