ClientSocket.java

package websocket.websocketHeap;

import java.util.concurrent.CountDownLatch;

import org.eclipse.jetty.websocket.api.Session;
import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
import org.eclipse.jetty.websocket.api.annotations.OnWebSocketError;
import org.eclipse.jetty.websocket.api.annotations.WebSocket;

@WebSocket
public class ClientSocket {
    private final CountDownLatch closeLatch;
    public ClientSocket(CountDownLatch closeLatch)
    {
        this.closeLatch = closeLatch;
    }
    @OnWebSocketConnect
    public void connect(Session session) {
        System.out.println("client: connected");
    }
    @OnWebSocketError
    public void error(Throwable cause) {
        System.out.println("client: error");
        cause.printStackTrace();
    }
    @OnWebSocketClose
    public void close(int code, String reason) {
        closeLatch.countDown();
        System.out.printf("client: close [%d] - [%d left]%n",code, closeLatch.getCount());
    }
}

ServerSocket.java

package websocket.websocketHeap;

import org.eclipse.jetty.websocket.api.Session;
import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
import org.eclipse.jetty.websocket.api.annotations.OnWebSocketError;
import org.eclipse.jetty.websocket.api.annotations.WebSocket;

@WebSocket
public class ServerSocket {

    @OnWebSocketConnect
    public void onWebSocketConnect(Session session) {
        System.out.println("server: connected");
        session.close();
    }

    @OnWebSocketError
    public void onWebSocketError(Throwable cause) {
        System.out.println("server: webSocketError");
        cause.printStackTrace();
    }

    @OnWebSocketClose
    public void onWebSocketClose(int statusCode, String reason) {
        System.out.println("server: closed");
    }

}

WebsocketTest.java

package websocket.websocketHeap;

import java.net.URI;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.websocket.client.ClientUpgradeRequest;
import org.eclipse.jetty.websocket.client.WebSocketClient;
import org.eclipse.jetty.websocket.server.WebSocketHandler;
import org.eclipse.jetty.websocket.server.WebSocketServerFactory;
import org.eclipse.jetty.websocket.servlet.ServletUpgradeRequest;
import org.eclipse.jetty.websocket.servlet.ServletUpgradeResponse;
import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;

public class WebsocketTest {
    private static WebSocketServerFactory serverFactory;

    public static void main(String[] args) throws Exception {
        Thread.sleep(20000);
        Server server = new Server(7004);
        server.setHandler(new WebSocketHandler() {
            @Override
            public void configure(WebSocketServletFactory factory) {
                WebsocketTest.serverFactory = (WebSocketServerFactory)factory;
                factory.setCreator((ServletUpgradeRequest req, ServletUpgradeResponse resp) -> {
                    return new ServerSocket();
                });
                factory.getPolicy().setIdleTimeout(1000 * 5);
            }
        });
        server.start();
        WebSocketClient client = new WebSocketClient();
        try {
            client.start();
            int clientCount = 1000;
            CountDownLatch clientCloseLatch = new CountDownLatch(clientCount);
            for (int i = 0; i < clientCount; i++) {
                createClient(client, clientCloseLatch);
            }
            clientCloseLatch.await(5,TimeUnit.MINUTES);
            System.out.println("All done");
            validateOpenSessions(serverFactory, client);
        } finally {
            client.stop();
            Thread.sleep(10000000);
            server.stop();
        }
    }

    private static void validateOpenSessions(WebSocketServerFactory server, WebSocketClient client)
    {
        System.out.printf("server.openSessions[%d]%n",server.getOpenSessions().size());
        System.out.printf("client.openSessions[%d]%n",client.getOpenSessions().size());
    }

    private static void createClient(WebSocketClient client, CountDownLatch clientCloseLatch) throws Exception {
        URI uri = URI.create("ws://localhost:7004/events/");
        ClientSocket socket = new ClientSocket(clientCloseLatch);
        ClientUpgradeRequest request = new ClientUpgradeRequest();
        client.connect(socket, uri, request);
    }
}