Embedded Technologies

Dear Forum,

I have some trouble with the CreMe virtual machine (NSICom) so I will just give it a try to post here. As NSICom support just does not answer my questions anymore (seems that I am already on there ignore list), I hope one of you can give me a hint on what's going wrong here.

The actual problem is a leaking of memory. After ages of reviewing my own code I figured out, that this is not my fault. Since it has something to do with threads, I wrote a simple test class:

import java.awt.BorderLayout;
import java.awt.*;
import java.io.*;
import java.net.*;
import java.text.SimpleDateFormat;
import java.util.*;

import javax.swing.*;
import javax.swing.*;

public class MemoryTest extends JFrame implements Runnable, ActionListener
{
    private final static short MODE_SSL = 1;

    private static final String AC_RUN_GC = "RUN_GC", AC_END = "END", AC_EXIT = "EXIT", AC_MEM_INFO = "MEM_INFO",
    AC_OBJECT_MAP = "OBJECT_MAP";

    private final short m_sMode;
    private int m_iCycles;
    private final Runnable runnable;
    private final Thread m_thCollector;
    private final LinkedList m_llThreads;
    private static URL testUrl;

    private JTextArea m_taLog;

    public MemoryTest(final short p_sMode, final int p_iCycles, final String p_strTestUrl)
    throws MalformedURLException
    {
        super("CreMe Memory tester");


        m_sMode = p_sMode;
        m_iCycles = p_iCycles;
        runnable = new Runnable()
        {
            public void run()
            {
                for (int i = 0; i < 100; i++)
                {
                    Math.random();
                    try
                    {
                        Thread.sleep(20);
                    }
                    catch (InterruptedException e)
                    {}
                }
            }
        };
        m_thCollector = new Thread()
        {
            public void run()
            {
                //... collect fiished threads
            }
        };
        m_llThreads = new LinkedList();
        testUrl = new URL(p_strTestUrl);

        initComponents();
    }

    public void run()
    {
        log("Starting test (MODE " + (m_sMode == MODE_SSL ? "SSL" : "THREAD") + " | CYCLES: " + m_iCycles + "...");
        long lLoopCount = 0;
        while (m_iCycles != 0)
        {
            switch (m_sMode)
            {
                case MODE_SSL:
                    runSSLTest();
                    break;
                default:
                    runThreadTest();
                break;

            }
            if (lLoopCount++ % 1000 == 0)
            {
                actionPerformed(new ActionEvent(this, 0, AC_MEM_INFO));
                actionPerformed(new ActionEvent(this, 0, AC_OBJECT_MAP));
            }
            synchronized (this)
            {
                if (m_iCycles > 0)
                {
                    m_iCycles--;
                }
            }
        }
        log("Test finished!");
    }

    private void runThreadTest()
    {
        while (m_llThreads.size() > 100)
        {
            sleep(100);
        }

        Thread t = new Thread(runnable);
        t.start();
        log("Started thread: " + t.getName());
        synchronized (m_llThreads)
        {
            m_llThreads.add(t);
        }
        if (!m_thCollector.isAlive())
        {
            m_thCollector.start();
        }
        sleep((int) (Math.random() * 100));
    }

    private void runSSLTest()
    {
        try
        {
            testUrl.openConnection();
        }
        catch (IOException e)
        {
            log("runSSLTest: " + e.getMessage());
            e.printStackTrace();
        }
    }

    private void initComponents()
    {
        // ... create ui
    }

    private final static SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yy_HHmmss: ");
    private void log(String p_strMsg)
    {
        // ... log to screen and file
    }

    private void sleep(final int p_iMillis)
    {
        try
        {
            Thread.sleep(p_iMillis);
        }
        catch (InterruptedException e)
        {}
    }

    public void actionPerformed(final ActionEvent e)
    {
        if (e.getActionCommand().equals(AC_END))
        {
            synchronized (this)
            {
                m_iCycles = 0;
            }
            log("Test canceled by user.");
        }
        else if (e.getActionCommand().equals(AC_MEM_INFO) || e.getActionCommand().equals(AC_RUN_GC))
        {
            if (e.getActionCommand().equals(AC_RUN_GC))
            {
                System.gc();
            }
            log("Free...: " + (Runtime.getRuntime().freeMemory() / 1024) + " kb\n");
            log("Total...: " + (Runtime.getRuntime().totalMemory() / 1024) + " kb\n");
        }
        else if (e.getActionCommand().equals(AC_EXIT))
        {
            log("Exiting application...");
            dispose();
            System.exit(0);
        }
        else if (e.getActionCommand().equals(AC_EXIT))
        {
            log("Printing object map of all objects...");
            creme.ObjectMap.printAll();
            log("...done");
        }
    }


    public static void main(final String[] args)
    {
        if (args.length != 3)
        {
            System.out.println("Parameter help: MODE(1=SSL,0=THREAD) CYCLES(-1=forever) URL(testURL for SSL test)");
            return;
        }

        try
        {
            new Thread(new MemoryTest(Short.parseShort(args[0]), Integer.parseInt(args[1]), args[2])).start();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}

I ran it from the command line like that and monitored the system's memory with the Windows CE performance monitor tool:

creme.exe -wd /Temp MemoryTester 0 -1 https://my.ssl.url/path/file.jsp

After about an hour it came to this: [monitor results|http://i625.photobucket.com/albums/tt340/swebble/crememem.png]
As you can see, the memory load of the system steadily increases. The heap memory of the application remains more or less on the same level of only a few kb. Can someone commit this problem or even figure out what's wrong?

When I use the SSL test mode which actually just opens ssl connections, the behavior is the same. I guess that the ssl implementation makes much use of threads internally.

Best regards and thanks in advance,

Sebastian