Threads of DICOM association remain in memory

[nroduit]

DICOM associations do not release properly. The TCPConnector lambda remains in memory even when everything is closed. After a certain number of iterations there are sometimes errors (changing to 20-50).

package org.dcm4che6.tool.echoscu;

import org.dcm4che6.conf.model.Connection;
import org.dcm4che6.data.UID;
import org.dcm4che6.net.AAssociate;
import org.dcm4che6.net.Association;
import org.dcm4che6.net.DicomServiceRegistry;
import org.dcm4che6.net.TCPConnector;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.TimeUnit;

public class MultipleEcho {
    public static void main(String[] args) throws Exception {
        String calling = "ECHOSCU";
        String called = "DICOMSERVER";
        String host = "dicomserver.co.uk";
        int port = 11112;
        for (int i = 0; i < 20; i++) {
            DicomServiceRegistry serviceRegistry = new DicomServiceRegistry();
            TCPConnector<Association> inst = new TCPConnector<>(
                    (connector, role) -> new Association(connector, role, serviceRegistry));
            CompletableFuture<Void> task = CompletableFuture.runAsync(inst);
            AAssociate.RQ rq = new AAssociate.RQ();
            rq.setCallingAETitle(calling);
            rq.setCalledAETitle(called);
            rq.putPresentationContext((byte) 1, UID.VerificationSOPClass, UID.ImplicitVRLittleEndian);
            Association as = inst.connect(new Connection(), new Connection().setHostname(host).setPort(port))
                    .thenCompose(as1 -> as1.open(rq))
                    .get(3000, TimeUnit.MILLISECONDS);
            as.cecho().get(3000, TimeUnit.MILLISECONDS);
            as.release();
            as.onClose().get(3000, TimeUnit.MILLISECONDS);
            task.cancel(true);
        }
        System.out.println("end");
    }
}

Breakpoint after the iterations:

In TCPConnector the run hangs in selector.select(this::onReady);?