Question

I was attempting to store all the JMS object of the class Message recieved in one minute into a tree map against its precise time as key.After completion of one minute, I wish to serialize the map and return the byte[] to another class. Meanwhile I create a new tree map to store the next set of JMS messages for a minute.

public class StoreMessage {

    private static long start_nanotime = System.nanoTime();
    private static Thread thisThread = Thread.currentThread();
    private static int timeToRun = 60000; // 1 minute
    private static byte[] b = null;
    public static Map<Long, Message> map1 = new TreeMap<Long, Message>();

    public static byte[] store(Message message) {

        new Thread(new Runnable() {

            public void run() {
                try {
                    sleep(timeToRun);
                    thisThread.interrupt();
                    b = serializer.serialize(map1);
                    new TreeMap<Long, Message>();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();

        while (!Thread.interrupted()) {
            long precise_time = TimeUnit.MILLISECONDS.toNanos(System.currentTimeMillis()) + (System.nanoTime()
                    - start_nanotime);
            map1.put(precise_time, message);

        }
        return b;
    }
}

This code is some how not working. Why? It is giving me error of java.lang.OutOfMemoryError: Java heap space Also I noticed that it keeps writing only one message to the map, ie if the messages were “hi”,”good day to you”–these are two jms messages; the StoreMessage class recieves one message at a time..ie it would first receive “hi” and once this message is processed, then it would retrieve the next message. But what i noticed is, for one whole minute, when the thread is not interrupted, it writes only the first message to the map and gives an error. How do i fix these?

Answer 1

The problem is that your map1 is never actually reset because the assignment is missing.

   public void run() {
                try {
                    sleep(timeToRun);
                    thisThread.interrupt();
                    b = serializer.serialize(map1);
                    map1 = new TreeMap<Long, Message>();  // Changed this line
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

Of course, you could also simply clear the map:

map1.clear();