Datagram stress test hangs.

Datagram stress test hangs.
The following test case runs for about 5 minutes, then it hangs.



import java.io.*;
import java.net.*;


class constant{
static public int threadcount = 50;
        static public boolean done = false;
        static public int port = 52456;
}
class client_thread extends Thread{

client_thread(){
super();
}
     public void run () {
try {
         InetAddress h1 = InetAddress.getLocalHost();
                 String k1 = h1.toString();
                 int j1 = k1.lastIndexOf("/");

                 DatagramSocket y1 = new DatagramSocket();
ByteArrayOutputStream x = new ByteArrayOutputStream();
DataOutputStream j = new DataOutputStream(x);
DatagramPacket y2;
for (int i=2000 ; i >= 0 ; i--){
j.writeInt(y1.getLocalPort());
byte mybytes[] = x.toByteArray();
y2 = new DatagramPacket(mybytes,mybytes.length,h1,constant.port);
y1.send(y2);
x.reset();
sleep(1);
}
j.writeInt(0);
byte mybytes[] = x.toByteArray();
y2 = new DatagramPacket(mybytes,mybytes.length,h1,constant.port);
y1.send(y2);
x.reset();
sleep(1);
}
catch(Exception e) {
e.printStackTrace();
System.out.print("TEST FAILED \\n");
};
     }
}


class server_client extends Thread {
Socket s;
int i;
server_client(){
super();
}
public void run() {
try {
int t =0;
int count = 1;
                 DatagramSocket y1 = new DatagramSocket(constant.port);
System.out.print("y1.getLocalPort() " + y1.getLocalPort() + " \\n");
ByteArrayOutputStream x = new ByteArrayOutputStream();
DataOutputStream j = new DataOutputStream(x);
j.writeInt(1);
byte mybytes[] = x.toByteArray();
DatagramPacket y2;
ByteArrayInputStream x1;
DataInputStream j1;
y2 = new DatagramPacket(mybytes,mybytes.length);
while (count <= constant.threadcount) {
y2 = new DatagramPacket(mybytes,mybytes.length);
y1.receive(y2);
x1 = new ByteArrayInputStream(y2.getData());
j1 = new DataInputStream(x1);
t = j1.readInt();
if (t == 0) {
count++;
}
else {
if (t != y2.getPort()) {
System.out.print("TEST FAILED \\n");
}
system.out.println(t);

}

}

                 System.out.print("y2.getLength() " + y2.getLength() + " \\n");
                 System.out.print("y2.getAddress() " + y2.getAddress().toString() + " \\n");


System.out.print("TEST PASSED \\n");
}
catch(Exception e) {
e.printStackTrace();
System.out.print("TEST FAILED \\n");
};
}

}

class java_net_DatagramSocket_methods {
    public static void main(String argv[]) throws Exception{
client_thread clients[] = new client_thread[100];
server_client server = new server_client();
server.start();
for (int i= 0; i<constant.threadcount ;i++){
clients[i] = new client_thread();
clients[i].start();
}
    }
}