Name: mf23781 Date: 07/17/98


Raised through here as Java Activator only has version 1.0 in
the bug submit form.

Using Java Plug-In 1.1 or 1.1.1, we have observed memory
leaks (worse under 1.1). Leaks occur using very basic
applets, with and without Swing, and not under a browser
VM or AppletViewer.

Failure can occur either via java.lang.OutOfMemoryError or
by hanging of the browser without notice. The usual failure
point is at a process mem usage of ~40Mb (my machine has
80Mb RAM and 91Mb swap) but it can expend the whole system
available memory. (Takes c. 5min with 1.1, c. 30min with 1.1.1).

Loss rates appear to be at least loosely related to class/
object quantities: smaller data items in our production
applet lose ~300k per invocation, larger ones up to ~3Mb.

Test Case:

import java.io.*;
import java.net.*;
import com.sun.java.swing.*;

public class MemoryTestFour extends JApplet
{
public void start()
{
JFrame aFrame = new JFrame();

java.awt.Container cp = aFrame.getContentPane();
cp.setLayout(new BoxLayout(cp, BoxLayout.Y_AXIS));

Runtime rt = Runtime.getRuntime();
long tm = rt.totalMemory();
long fm = rt.freeMemory();

cp.add(new JLabel("Total memory: "+tm));
cp.add(new JLabel("Free memory: "+fm));
cp.add(new JLabel("Used memory: "+(tm-fm)));

aFrame.pack();
aFrame.show();

try
{
Thread.sleep(1000);
}
catch (Exception e)
{
}

aFrame.dispose();

try
{
getAppletContext().showDocument(new java.net.URL(getParameter("URL")));
}
catch (Exception e)
{
System.out.println(e);
}
}
}

When called from HTML it needs a parameter 'URL', which is the
URL of the page itself (so that the referesh is automated).
Note that under Plug-In 1.1.1 the time for Explorer to crash
can be c. 1/2hr ---- try it under 1.1 and it's c. 5min.
In either case, the total and used memory counts can be seen
to rise, certainly after a minute or so.
The Swing components can be swapped for AWT and the end result
is the same.
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