Non-heap memory area spring leak in JVM 1.50_6

Question

Please let me question though it doesn't understand be good from this topic.
A problem occurs when testing as follows.
The problem is to generate memory leak in non-heap area.
%java CconnectTest2 129.24.34.68 130.104.10.50 6101 5000 185000 100
(%java -server CconnectTest2 source-ipaddress destination-ipaddress src-port dst-port thread-count)
CconnectTest2.java
import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketTimeoutException;
import java.net.UnknownHostException;
import java.nio.channels.IllegalBlockingModeException;
import java.util.Calendar;
public class CconnectTest2 {
     * @param bind_ip connect_ip connect_port wait_cntconnect_TIMEOUT thread_cnt
     public static void main(String[] args) {
          if ((args[0].equals("")) || (args[0]==null)) {
     System.err.println("bind_ip*");
     return ;
          if ((args[1].equals("")) || (args[1]==null)) {
     System.err.println("connect_ip*");
     return ;
          if ((args[2].equals("")) || (args[2]==null)) {
     System.err.println("connect_port*");
     return ;
          if ((args[3].equals("")) || (args[3]==null)) {
     System.err.println("wait_cnt*");
     return ;
          if ((args[4].equals("")) || (args[4]==null)) {
     System.err.println("connect_TIMEOUT*");
     return ;
          if ((args[5].equals("")) || (args[5]==null)) {
     System.err.println("thread_cnt*");
     return ;
String bind_ip          =args[0];
String connect_ip     =args[1];
int connect_port     =Integer.parseInt(args[2]);
int wait_cnt          =Integer.parseInt(args[3]);
int connect_TIMEOUT     =Integer.parseInt(args[4]);
int thread_cnt          =Integer.parseInt(args[5]);
System.out.println("bind_ip="+bind_ip);
System.out.println("connect_ip="+connect_ip);
System.out.println("connect_port="+connect_port);
System.out.println("wait_cnt="+wait_cnt);
System.out.println("connect_TIMEOUT="+connect_TIMEOUT);
System.out.println("thread_cnt="+thread_cnt);
int i=0;
while( true ){
i++;
if( i<= thread_cnt){
     ConnectExe a = new ConnectExe(connect_ip,bind_ip,connect_port,connect_TIMEOUT,wait_cnt) ;
a.start() ;
try {
Thread.sleep( 1000 ) ;
} catch (InterruptedException ex) {
     System.out.println("thread_start[ "+i+"]");
} else {
System.out.println("thread_start OK"+thread_cnt);
     break ;
while( true ){
System.gc() ;
try {
Thread.sleep( 20000 ) ;
} catch (InterruptedException ex) {
int hour = Calendar.getInstance().get(Calendar.HOUR_OF_DAY) ;
int min = Calendar.getInstance().get(Calendar.MINUTE) ;
int sec = Calendar.getInstance().get(Calendar.SECOND) ;
Runtime run = Runtime.getRuntime();
long freesize = 0 ;
freesize = (run.maxMemory()-run.totalMemory())+run.freeMemory() ;
if( freesize > 0 ){
freesize = freesize/1024 ;
System.out.println( "" + hour + ":" + min + ":" + sec
          + " HeepFreeSize:"+ freesize + " K"
+ " activeThread:" + Thread.activeCount() ) ;
static public class ConnectExe extends Thread{
String      serverAddress=null;
String      bindip=null;
int          port=6100;
int          timeout=0;
int          wait_cnt=0;
public ConnectExe(String ne,String bind,int connect_port,int timeout,int wait_cnt ){
     this.serverAddress           = ne ;
this.bindip                = bind ;
this.port                     = connect_port ;
this.timeout               = timeout;
this.wait_cnt               = wait_cnt;
public void run(){
while( true ){
     SocketAddress socketAddress = null;
     Socket socket = null;
     try {
          socket = new Socket();
          socket.setKeepAlive(true);
          byte[] ip = InetAddress.getByName(this.serverAddress).getAddress();
          InetAddress addr = InetAddress.getByAddress(this.serverAddress, ip);
          if (bindip == null) {
               socketAddress = new InetSocketAddress(addr, this.port);
          } else {
               socketAddress = new InetSocketAddress(addr, this.port);
               SocketAddress bindAddress = new InetSocketAddress(this.bindip, socket.getPort());
               socket.bind(bindAddress);
          System.out.println( "connect:" + this.serverAddress ) ;
          socket.connect(socketAddress, this.timeout);
          socket.close();
          System.out.println( "close :" + this.serverAddress ) ;
          socket = null;
     } catch (UnknownHostException e) {
          System.out.println("This socket cannot be connected with the server(UnknownHostException) " + e.getMessage() ) ;
          if (socket != null) {
               try {
                    socket.close();
               } catch (IOException e1) {
                    System.out.println( e1.getMessage() ) ;
               socket                = null;
               socketAddress      = null;
     } catch (SocketTimeoutException e) {
          System.out.println("This socket cannot be connected with the server (SocketTimeoutException) " + e.getMessage() ) ;
          if (socket != null) {
               try {
                    socket.close();
               } catch (IOException e1) {
                    System.out.println( e1.getMessage() ) ;
               socket                = null;
               socketAddress      = null;
     } catch (IllegalBlockingModeException e) {
          System.out.println("This socket cannot be connected with the server (IllegalBlockingModeException) " + e.getMessage() ) ;
          if (socket != null) {
               try {
                    socket.close();
               } catch (IOException e1) {
                    System.out.println( e1.getMessage() ) ;
               socket                = null;
               socketAddress      = null;
     } catch (IllegalArgumentException e) {
          System.out.println("This socket cannot be connected with the server (IllegalArgumentException) " + e.getMessage() ) ;
          if (socket != null) {
               try {
                    socket.close();
               } catch (IOException e1) {
                    System.out.println( e1.getMessage() ) ;
               socket                = null;
               socketAddress      = null;
     } catch (IOException e) {
          System.out.println("This socket cannot be connected with the server (IOException) " + e.getMessage() ) ;
          if (socket != null) {
               try {
                    socket.close();
               } catch (IOException e1) {
                    System.out.println( e1.getMessage() ) ;
               socket                = null;
               socketAddress      = null;
     } catch (Exception e) {
     System.out.println("This socket cannot be connected with the server (Exception) " + e.getMessage() ) ;
     if (socket != null) {
          try {
               socket.close();
          } catch (IOException e1) {
               System.out.println( e1.getMessage() ) ;
          socket                = null;
          socketAddress      = null;
try {
                         Thread.sleep( this.wait_cnt ) ;
                    } catch (InterruptedException e) {
It leaks gradually when executing it for a long time.
It makes the generation of the memory leak disregarding timeout error of the
connection a problem.
Is this a bug of JVM?
Or, is it a problem of coding?
Environment:
JVM Sun JVM 1.5.0_6
OS RedHat Enterprise Linux ES 3 update6 (kernel 2.4.21-37ELsmp)

Answer 1

I was searching on Google for "java Calendar memory leak", and I ran across this post. Now, I haven't examined your code but I do see you make a lot of calls to getInstance() in java.util.Calendar, and I am having the same kind of issue as you are describing. So I took the Calendar class out (no more getInstances) and now the memory is still increasing but at a MUCH slower rate, and the CPU time is down drastically. I do not know if this is the cause because I haven't seen it documented, but it would be great if someone could confirm this for me. Maybe try removing the Calendar getInstances and find another way to do it, like using System.getCurrentMillis and working from there to get the hours (that's what I did.)
Hope this helps,
Elijah