ConcurrentHashMap shared with 2 threads

Question

Hello Guys,
I would be really happy if you could help me.
I am having a main program which creates a ConcurrentHashMap and adds key-value pairs to this CHM.
A second thread should iterate over this CHM at the same time and delete expired entries (right now all values mod5 = 0). Unfortunately every time the second thread finds an expired entry, it deletes all elements saved in this list.
What can I do to make this work?
Here the code of my testing program:
//### MAIN #####
import java.util.HashMap;
import java.util.concurrent.ConcurrentHashMap;
public class Main {
      * @param args
     public static void main(String[] args) {
          ConcurrentHashMap<Integer, TestContainer> chm = new ConcurrentHashMap<Integer, TestContainer>();
          TestContainer tc = new TestContainer(0,0);
          CleanerThread cleanT = new CleanerThread(chm);
          cleanT.start();
          for(int i = 0; i < 100; i++){
               tc.index = i;
               tc.value = (int) (Math.random()*10);
               System.out.println("1 Thread: Creating ["+tc.index+"="+tc.value+"]");
               chm.put(i, tc);
               System.out.println(chm.size());
               try {
                    Thread.sleep(1000);
               } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
//### Thread ###
import java.util.Iterator;
public class CleanerThread extends Thread {
     ConcurrentHashMap<Integer, TestContainer> chm;
     Iterator it;
     public CleanerThread(ConcurrentHashMap<Integer, TestContainer> chm) {
          this.chm = chm;
     @Override
     public void run() {
          TestContainer tc;
          while (true) {
               it = chm.values().iterator();
               while (it.hasNext()) {
                    tc = (TestContainer) it.next();
                    if ((tc.value % 5) == 0) {
                         System.out.println("2 Thread: Removing ["+tc.index+"="+tc.value+"]");
                         it.remove();
               try {
                    Thread.sleep(3000);
               } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
//### Container ###
public class TestContainer {
     public int index;
     public int value;
     public TestContainer(int index, int value) {
          super();
          this.index = index;
          this.value = value;
/*### Output ###
1 Thread: Creating [0=6]
1 Thread: Element count = 1
1 Thread: Creating [1=9]
1 Thread: Element count = 2
1 Thread: Creating [2=4]
1 Thread: Element count = 3
1 Thread: Creating [3=2]
1 Thread: Element count = 4
1 Thread: Creating [4=4]
1 Thread: Element count = 5
1 Thread: Creating [5=5]
1 Thread: Element count = 6
2 Thread: Removing [5=5]
2 Thread: Removing [5=5]
2 Thread: Removing [5=5]
2 Thread: Removing [5=5]
2 Thread: Removing [5=5]
2 Thread: Removing [5=5]
1 Thread: Creating [6=4]
1 Thread: Element count = 1
1 Thread: Creating [7=6]
1 Thread: Element count = 2
1 Thread: Creating [8=3]
1 Thread: Element count = 3
1 Thread: Creating [9=0]
1 Thread: Element count = 4
1 Thread: Creating [10=6]
1 Thread: Element count = 5
1 Thread: Creating [11=4]
1 Thread: Element count = 6
1 Thread: Creating [12=8]
1 Thread: Element count = 7
1 Thread: Creating [13=9]
1 Thread: Element count = 8
1 Thread: Creating [14=1]
1 Thread: Element count = 9
1 Thread: Creating [15=8]
1 Thread: Element count = 10
1 Thread: Creating [16=7]
1 Thread: Element count = 11
1 Thread: Creating [17=3]
1 Thread: Element count = 12
1 Thread: Creating [18=6]
1 Thread: Element count = 13
1 Thread: Creating [19=3]
1 Thread: Element count = 14
1 Thread: Creating [20=3]
1 Thread: Element count = 15
1 Thread: Creating [21=4]
1 Thread: Element count = 16
1 Thread: Creating [22=7]
1 Thread: Element count = 17
1 Thread: Creating [23=3]
1 Thread: Element count = 18
1 Thread: Creating [24=5]
1 Thread: Element count = 19
1 Thread: Creating [25=8]
1 Thread: Element count = 20
1 Thread: Creating [26=3]
1 Thread: Element count = 21
1 Thread: Creating [27=9]
1 Thread: Element count = 22
1 Thread: Creating [28=1]
1 Thread: Element count = 23
1 Thread: Creating [29=1]
1 Thread: Element count = 24
1 Thread: Creating [30=3]
1 Thread: Element count = 25
1 Thread: Creating [31=5]
1 Thread: Element count = 26
1 Thread: Creating [32=9]
1 Thread: Element count = 27
1 Thread: Creating [33=2]
1 Thread: Element count = 28
1 Thread: Creating [34=9]
1 Thread: Element count = 29
1 Thread: Creating [35=2]
1 Thread: Element count = 30
1 Thread: Creating [36=3]
1 Thread: Element count = 31
1 Thread: Creating [37=8]
1 Thread: Element count = 32
1 Thread: Creating [38=2]
1 Thread: Element count = 33
1 Thread: Creating [39=9]
1 Thread: Element count = 34
1 Thread: Creating [40=0]
1 Thread: Element count = 35
1 Thread: Creating [41=7]
1 Thread: Element count = 36
1 Thread: Creating [42=1]
1 Thread: Element count = 37
1 Thread: Creating [43=1]
1 Thread: Element count = 38
1 Thread: Creating [44=5]
1 Thread: Element count = 39
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
2 Thread: Removing [44=5]
1 Thread: Creating [45=9]
1 Thread: Element count = 1
1 Thread: Creating [46=5]
1 Thread: Element count = 2
1 Thread: Creating [47=4]
1 Thread: Element count = 3
1 Thread: Creating [48=5]
1 Thread: Element count = 4
*/

Answer 1

Actually the session is closed as soon as I delete the key-value pair out of the map. If we get back to my example, you think all I need to do is this to have it concurrent (sounds almost to easy :) )?
public class CleanerThread extends Thread {
     ConcurrentHashMap<Integer, TestContainer> chm;
     Iterator it;
     public CleanerThread(ConcurrentHashMap<Integer, TestContainer> chm) {
          this.chm = chm;
     @Override
     public void run() {
          TestContainer tc;
          while (true) {
               it = chm.values().iterator();
               while (it.hasNext()) {
                    tc = (TestContainer) it.next();
                    if ((tc.value % 2) == 0) {
                         System.out.println("2 Thread: Removing ["+tc.index+"="+tc.value+"]");
                         //it.remove();
                                        //HERE
                         chm.remove(tc.index, tc);
                                                //or chm.remove(tc.index);
                                        //TO HERE
               try {
                    Thread.sleep(10000);
               } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
}Edited by: Varox on Aug 14, 2008 5:19 AM