[jdom-interest] memory question?

[Guanming Wu]

Hi Jason,

Yes, I agree with you. I use both jdk1.2.2 and jdk1.3.0 under win32 and
linux.

Thanks.

Guanming


On Sun, 7 Jan 2001, Jason Hunter wrote:

> I'm seeing similar behavior.  But watching in OptimizeIt I see the
> objects do get collected when memory maxes out.  Seems GC just isn't
> eager to collect the objects until it's necessary.  If I run the test on
> a large file (enough to get memory mostly consumed) and then a medium
> sized file (just enough to poke memory usage over the max) I see very
> little memory used afterward.
> 
> I'm going to chalk it up to weird GC behavior unless someone has ideas.
> 
> BTW, I'm using Sun's JDK 1.2.2 on Win2K.  You too?
> 
> -jh-
> 
> > Guanming Wu wrote:
> > 
> > It seems to me that it is very difficult for garbage collector (gc) to
> > collect jdom document and element objects. Here is a test program:
> > 
> > import java.io.*;
> > import org.jdom.*;
> > import org.jdom.input.*;
> > 
> > public class XMLMemoryTest extends Object {
> > 
> >     public XMLMemoryTest(String file) {
> >         loadXML(file);
> >     }
> > 
> >     private void loadXML(String file) {
> >         try {
> >             SAXBuilder builder = new SAXBuilder(false);
> >             Document doc = builder.build(new File(file));
> >             Element root = doc.getRootElement();
> >             root = null;
> >             doc = null;
> >             file = null;
> >             gc();
> >         }
> >         catch(Exception e) {
> >             e.printStackTrace();
> >         }
> >     }
> >      /** This method is from the book Java Platform Performace by
> > Wilson, S & Kesselman, J. */
> >      private void gc() {
> >         try {
> >             System.gc();
> >             Thread.currentThread().sleep(100);
> >             System.runFinalization();
> >             Thread.currentThread().sleep(100);
> >             System.gc();
> >             Thread.currentThread().sleep(100);
> >             System.runFinalization();
> >             Thread.currentThread().sleep(100);
> >         }
> >         catch(Exception e) {
> >             e.printStackTrace();
> >         }
> >     }
> > }
> > 
> > import java.io.*;
> > 
> > public class XMLMemoryTestRunner extends Object {
> > 
> >     public static void main(String args[]) {
> >         if (args.length < 1) {
> >             System.out.println("Usage java test.XMLMemoryTest
> > xmlfile");
> >             return;
> >         }
> >         memoryInfo("Before loading: ");
> >         XMLMemoryTest test = new XMLMemoryTest(args[0]);
> >         test = null;
> >         memoryInfo("After loading: ");
> >         try {
> >             BufferedReader reader = new BufferedReader(new
> > InputStreamReader(System.in));
> >             String line = null;
> >             while (true) {
> >                 line = reader.readLine();
> >                 if (line.equalsIgnoreCase("quit")) break;
> >                 if (line.equalsIgnoreCase("check"))
> > memoryInfo("Memory: ");
> >             }
> >         }
> >         catch(IOException e) {
> >             e.printStackTrace();
> >         }
> >     }
> > 
> >     protected static void memoryInfo(String label) {
> >         long total = Runtime.getRuntime().totalMemory();
> >         long free = Runtime.getRuntime().freeMemory();
> >         System.out.println(label + " total " + total + " usage " +
> > (total - free));
> >     }
> > }
> > 
> > Compile them and run XMLMemoryTestRunner.
> > 
> > I tested with an 1M XML file, the memory about 8000M could not be
> > released. I am wondering if there are any problems with my codes?
> > 
> > Thanks.
> > 
> > Guanming
> >
> 
> 
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