I've got a strange memory leak that I'm trying to understand and find
a way to fix or get around. The problem was first reported by a
customer who found that after running for a very long time, my
software becomes very slow and unresponsive. This turned out to be
due to a slow increase in the amount of memory being used, as shown
in Activity Monitor. After much investigation, I've found a simple
test case that illustrates the problem. This consists of a JLabel
displayed in a JFrame, with the text of the JLabel being very
frequently updated:
import java.awt.*;
import javax.swing.*;
public class Memory_Leak extends JFrame {
public Memory_Leak() {
super("Memory_Leak");
JLabel label = new JLabel();
label.setPreferredSize(new Dimension(200, 100));
getContentPane().add(label, BorderLayout.CENTER);
pack();
setVisible(true);
for (long i=0; i<100000000; i++) {
label.setText(String.valueOf(i));
}
}
public static void main(String args[]) {
new Memory_Leak();
}
}
When this little program is run (which typically takes several
minutes), the real memory consumption as displayed in Activity
Monitor slowly grows and grows and grows, by about 3MB in the test
I've just run. Monitoring with JConsole shows that both heap and non-
heap memory remain roughly constant, but the total number of classes
loaded grows linearly with time from about 1,700 to 14,000 during
execution. This class loading looks odd to me, but maybe it's normal
- I don't understand what goes on in the depths of a JVM. I've not
bothered trying to analyse heap dumps, as the constant heap size
suggests that I would be wasting my time. One other thing I've
noticed is that the leak seems to be many times faster with OSX 10.4
than OSX 10.5/6.
Does anyone understand what's going on here, and/or how I remove the
memory leak?
Thanks in advance.
Russ Calvert
AstroGrav Astronomy Software
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