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package garbage;
import java.io.Closeable;
import java.util.ArrayList;
/**
* This code to try to understand a GC strategy.
* IMHO the first object in the main should be reclaimed: it is not!
* why?
* I suspect a bug in the mark and sweep due to cycles ....
*/
public class TestReachable {
/*
* these object are not immmediately garbaged since they are referenced
* from a static ArrayList
*/
static class Closer implements Closeable {
Object thing ;
Closer(Object thing ){
this.thing = thing ;
}
public void close() {
System.out.println("CLOSING");
}
}
static class SafeCloser {
static ArrayList<Closer> closerList = new ArrayList<Closer>() ;
Closer closer ;
SafeCloser(Closer clos) {
this.closer = clos ;
closerList.add(clos) ;
}
public void finalize() {
System.out.println("FINALIZE safeCloser");
closerList.remove(closer) ;
closer.close() ;
}
}
static class ReclaimableObject {
public void finalize() {
System.out.println("FINALIZE A "
+ name + " ;thing : " + thing +" ; safe: " + safe) ;
}
Object thing ;
Closer closer ;
SafeCloser safe ;
String name ;
ReclaimableObject (String name ,boolean withObject, boolean withSafe) {
this.name = name ;
if(withObject) {
this.thing = new Object() ;
}
this.closer = new Closer(thing) ;
if(withSafe) {
this.safe = new SafeCloser(closer) ;
}
}
}
public static void main(String[] args) throws Exception {
// this object will NOT be reclaimed
ReclaimableObject object = new ReclaimableObject("ONE" ,true, true) ;
object = null ;
// this object will be reclaimed
ReclaimableObject object2 = new ReclaimableObject("TWO" ,false, true) ;
object2 = null ; // this object will be reclaimed
ReclaimableObject object3 = new ReclaimableObject("THREE", true, false) ;
object3 = null ;
for(int ix = 0 ; ix < 10000 ; ix++) {
long[] array = new long[1000] ;
}
Thread.sleep(3000L );
System.out.println("MID WAY");
// this object WILL be reclaimed !!!!! (go figure!)
object= new ReclaimableObject("ONE-2" ,true, true) ;
object= null ;
// this object will be reclaimed
object2 = new ReclaimableObject("TWO-2" ,false, true) ;
object2 = null ;
// this object will be reclaimed
object3 = new ReclaimableObject("THREE-2", true, false) ;
object3 = null ;
for(int ix = 0 ; ix < 10000 ; ix++) {
long[] array = new long[1000] ;
}
Thread.sleep(3000L );
System.out.println("THE END");
}
} |
comment tracer un Objet dont le GC ne veut pas?
Répondre avec citation
Tu ne peux pas prévoir le moment où tes objets seront collectés, ni dans quel ordre ils le seront. Le GC peut très bien conservé en mémoire un objet très "longtemps" après qu'il ne soit plus accessible.
Envoyé par adiGuba
)
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