Game server: Map managing questions

Question

Hello everyone,
I'm trying to develop some kind of RPG. I have different issues, where I need advice:
1) Map(2D) managment on game server
The map I want to keep in memory on server will contain objects such as: Item, NPC, Character, etc.
Item, NPC, Character and other objects going to extend MapObject class, because I want to keep all this data in same place.
Let's suppose that the map will have 50x50 tiles..
I want to use Hashtable array to store elements there... So I will have something like this:
Hashtable <String, MapObject>[][] map = new Hashtable[50][50];
String(aka key) is going to be object_name + "_" + object_id..
The questions are:
- What about performance in this situation?
- Is there any other data structure which can suite better to this situation?
2) The other question I have is about sending map object(once in fixed period of time) and updates(for example some character walked or picked an item).
The architecture I thought for sending data to client is:
TCP Connection for authentication anc chat
MultiCast Socket for synchronizing map object and sending updates
- Is this aceptable architecture for server?
- Is MultiCast socket good for sending updates and map object?(because there will be significant gain in term of computation on server, comparing to TCP, but what about losses of packets? what about traffic? what kind of protections(excluding timeouts) should I implement on client-side? )
Thank you in advance.

Answer 1

patriot87 wrote:
Strange... I have also tried with 200k and same results... :D
How comes?Well, one reason is that your test is broken. The first set of tests will always take longer, cause it's before hotspot has kicked in, etc. I moved the test to a method, precreated the objects (remember, if gc happens in one and not the other it's a huge difference), and called them repeatedly. Once I did that, there wasn't really a noticeable difference between them:
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;
import java.util.Random;
public class HashMapTest
   private static MapObject[] objs = new MapObject[200000];
   private static Random gen = new Random();
   public static void main(String [] agrs)
      for ( int i = 0; i < objs.length; i++ ) {
         objs[i] = new MapObject("ID" + i, "NAME"+i);
      hashMap();
      hashTable();
      hashMap();
      hashTable();
      hashMap();
      hashTable();
      hashMap();
      hashTable();
   private static void hashMap() {
      doTest(new HashMap<String, MapObject>());
   private static void hashTable() {
      doTest(new Hashtable<String, MapObject>());
   private static void doTest(Map<String, MapObject> map) {
      long start_time = System.currentTimeMillis();
      for (int i = 0; i < objs.length; i++)
         map.put(objs.id , objs[i]);
for (int i = 0; i < objs.length; i++)
int randomInt = gen.nextInt(objs.length);
map.get("ID" + randomInt);
System.out.println(map.getClass() + ": " + (System.currentTimeMillis() - start_time));
class MapObject
String name;
String id;
public MapObject (String id, String name)
this.id = id;
this.name = name;
}Results of one arbitrary test:
[pre]class java.util.HashMap: 343
class java.util.Hashtable: 500
class java.util.HashMap: 313
class java.util.Hashtable: 328
class java.util.HashMap: 453
class java.util.Hashtable: 313
class java.util.HashMap: 296
class java.util.Hashtable: 454[/pre]
Edited by: endasil on 13-Nov-2009 10:34 AM