Question

I’m running the following program. The main thread runs and terminates normally but the program continues to run because of a thread called pool-1-thread-1, which never terminates. Can anyone suggest what is wrong with the code? The configuration files are all as supplied in the standard distribution of Solr.

package solrapp;

import org.apache.solr.client.solrj.SolrQuery;
import org.apache.solr.client.solrj.SolrServer;
import org.apache.solr.client.solrj.embedded.EmbeddedSolrServer;
import org.apache.solr.client.solrj.response.QueryResponse;
import org.apache.solr.common.SolrDocumentList;
import org.apache.solr.core.CoreContainer;

public class SolrApp {

    public static void main(String[] args) throws Exception {
        CoreContainer coreContainer = new CoreContainer.Initializer().initialize();
        SolrServer server = new EmbeddedSolrServer(coreContainer, null);
        SolrQuery query = new SolrQuery("*:*");
        QueryResponse response = server.query(query);
        SolrDocumentList results = response.getResults();
        System.out.println(results);
    }
}

Answer 1

It appears that the CoreContainer class has a method called shutdown.

Although I haven’t tried it myself, I would guess that adding the following line after printing out the results should stop all the threads:

coreContainer.shutdown();

My guess would be that the CoreContainer is starting up a thread pool to accept queries, so one should tell the object that started up the pool to stop those threads so that all threads on the JVM can gracefully shutdown.