i have a server at the moment which makes a new thread for every user connected but after about 6 people are on the server for more than 15 mins it tends to flop and give me java heap out of memory error i have 1 thread that checks with a mysql database every 30 seconds to see if any of the users currently logged on have any new messages. what would be the easiest way to implement a server queue?

this is the my main method for my server:

public class Server {

    public static int MaxUsers = 1000;
    //public static PrintStream[] sessions = new PrintStream[MaxUsers];
    public static ObjectOutputStream[] sessions = new ObjectOutputStream[MaxUsers];
    public static ObjectInputStream[] ois = new ObjectInputStream[MaxUsers];
    private static int port = 6283;
   public static Connection conn;
       static Toolkit toolkit;
    static Timer timer;

    public static void main(String[] args) {
        try {
            conn = (Connection) Mysql.getConnection();
        } catch (Exception ex) {
            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
        }
        System.out.println("****************************************************");
        System.out.println("*                                                  *");
        System.out.println("*                    Cloud Server                  *");
        System.out.println("*                       ©2010                      *");
        System.out.println("*                                                  *");
        System.out.println("*                   Luke Houlahan                  *");
        System.out.println("*                                                  *");
        System.out.println("* Server Online                                    *");
        System.out.println("* Listening On Port " + port + "                           *");
        System.out.println("*                                                  *");
        System.out.println("****************************************************");
        System.out.println("");
        mailChecker();
        try {
            int i;
            ServerSocket s = new ServerSocket(port);
            for (i = 0; i < MaxUsers; ++i) {
                sessions[i] = null;
            }
            while (true) {
                try {
                    Socket incoming = s.accept();                    
                    boolean found = false;
                    int numusers = 0;
                    int usernum = -1;
                    synchronized (sessions) {
                        for (i = 0; i < MaxUsers; ++i) {
                            if (sessions[i] == null) {
                                if (!found) {
                                    sessions[i] = new ObjectOutputStream(incoming.getOutputStream());
                                    ois[i]= new ObjectInputStream(incoming.getInputStream());
                                    new SocketHandler(incoming, i).start();
                                    found = true;
                                    usernum = i;
                                }
                            } else {
                                numusers++;
                            }
                        }
                        if (!found) {
                            ObjectOutputStream temp = new ObjectOutputStream(incoming.getOutputStream());
                            Person tempperson = new Person();
                            tempperson.setFlagField(100);
                            temp.writeObject(tempperson);
                            temp.flush();
                            temp = null;
                            tempperson = null;
                            incoming.close();
                        } else {
                        }
                    }
                } catch (IOException ex) {
                    System.out.println(1);
                    Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        } catch (IOException ex) {
            System.out.println(2);
            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
        public static void mailChecker() {
        toolkit = Toolkit.getDefaultToolkit();
        timer = new Timer();
        timer.schedule(new mailCheck(), 0, 10 * 1000);
    }
}