tests/gc/Final.java

   1 import java.util.Vector;
   2 import java.util.Enumeration;
   3
   4 public class Final {
   5         public static final int N=20;
   6         public static final int SLEEP=1000;
   7         public static final int MOD_REMEMBERED =3;
   8         public static final int MOD_RESURRECTED=4;
   9         public static final int MOD_UGLY       =10;
  10
  11         public static Vector<Final> resurrected;
  12         public static Vector<Final> remembered;
  13
  14         public int id;
  15
  16         protected void finalize() throws Throwable {
  17                 System.out.println("\tFinalized object #" + id);
  18
  19                 if (id % MOD_RESURRECTED == 0) {
  20                         System.out.println("\tFinalizer #" + id + " resurrected object");
  21                         resurrected.add(this);
  22                 }
  23
  24                 if (id % MOD_UGLY == 0) {
  25                         System.out.println("\tFinalizer #" + id + " does an ugly thing!");
  26                         System.gc();
  27                 }
  28
  29                 super.finalize();
  30         }
  31
  32         public static void main(String args[]) {
  33                 Enumeration<Final> en;
  34                 Final f = null;
  35
  36                 resurrected = new Vector<Final>(N);
  37                 remembered  = new Vector<Final>(N);
  38
  39                 System.out.println("Creating objects ...");
  40                 for (int i=0; i<N; i++) {
  41                         f = new Final();
  42                         f.id = i;
  43
  44                         if (i % MOD_REMEMBERED == 0) {
  45                                 System.out.println("\tRemembering object #" + i);
  46                                 remembered.add(f);
  47                         }
  48
  49                 }
  50                 f = null;
  51
  52                 System.out.println("Forcing collection 1 ...");
  53                 System.gc();
  54                 System.out.println("Forcing collection 2 ...");
  55                 System.gc();
  56                 System.out.println("Forcing collection 3 ...");
  57                 System.gc();
  58
  59                 for (long i=0; i<400000000; i++);
  60                 /*try {
  61                         Thread.sleep(SLEEP);
  62                 } catch (Exception e) {
  63                 }*/
  64
  65                 en = remembered.elements();
  66                 while (en.hasMoreElements()) {
  67                         f = en.nextElement();
  68                         System.out.println("Preserved object #" + f.id);
  69                 }
  70
  71                 en = resurrected.elements();
  72                 while (en.hasMoreElements()) {
  73                         f = en.nextElement();
  74                         System.out.println("Resurrected object #" + f.id);
  75                 }
  76
  77                 f = null;
  78                 remembered = null;
  79                 resurrected = null;
  80
  81                 System.out.println("Forcing collection 4 ...");
  82                 System.gc();
  83                 System.out.println("Forcing collection 5 ...");
  84                 System.gc();
  85
  86                 for (long i=0; i<400000000; i++);
  87                 /*try {
  88                         Thread.sleep(SLEEP);
  89                 } catch (Exception e) {
  90                 }*/
  91
  92                 System.out.println("Shutting down ...");
  93                 System.exit(0);
  94         }
  95 }