Class.forName cause ClassLoader objects moved to tenured generation

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Hi all,

I have seen Class.forName() causes the tenured generation got filled with custom ClassLoader objects. I suspect something JVM done internally will move the ClassLoader objects to tenured generation. For example, the following code:
========================
public class Test  {
   public static void main(String[] args) throws Exception {
     for (int i=0 ;i<30000;i++) {
         test();
     }
   }
   private static void test() throws Exception {
     MyClassLoader mcl = new MyClassLoader();
     Class.forName("java.lang.String", false, mcl);
   }
}

public class MyClassLoader extends ClassLoader {}
=========================
will output gc log:

[GC [DefNew: 512K->64K(576K), 0.0041095 secs] 512K->344K(1984K), 0.0042064 secs]
[GC [DefNew: 576K->64K(576K), 0.0032096 secs] 856K->682K(1984K), 0.0032937 secs]
[GC [DefNew: 575K->63K(576K), 0.0032085 secs] 1194K->1021K(1984K), 0.0033686 secs]
[GC [DefNew: 575K->64K(576K), 0.0025146 secs] 1533K->1359K(1984K), 0.0026305 secs]
[GC [DefNew: 576K->64K(576K), 0.0025942 secs][Tenured: 1634K->166K(1664K), 0.0169541 secs] 1871K->166K(2240K), 0.0197106 secs]
[GC [DefNew: 512K->64K(576K), 0.0019209 secs] 678K->505K(1984K), 0.0020053 secs]
[GC [DefNew: 576K->63K(576K), 0.0022846 secs] 1017K->844K(1984K), 0.0024271 secs]
[GC [DefNew: 575K->63K(576K), 0.0023358 secs] 1356K->1182K(1984K), 0.0024235 secs]
[GC [DefNew: 575K->64K(576K), 0.0025660 secs][Tenured: 1457K->166K(1536K), 0.0136841 secs] 1694K->166K(2112K), 0.0164004 secs]


If change the Class.forName to loadClass:
========================
private static void test() throws Exception {
    MyClassLoader mcl = new MyClassLoader();
    mcl.loadClass("java.lang.String");
}
========================
then gc log will be:

[GC [DefNew: 512K->63K(576K), 0.0028769 secs] 512K->138K(1984K), 0.0029627 secs]
[GC [DefNew: 575K->0K(576K), 0.0009856 secs] 650K->138K(1984K), 0.0010711 secs]
[GC [DefNew: 512K->0K(576K), 0.0006255 secs] 650K->138K(1984K), 0.0007062 secs]
[GC [DefNew: 512K->0K(576K), 0.0002065 secs] 650K->138K(1984K), 0.0002861 secs]
[GC [DefNew: 512K->0K(576K), 0.0001936 secs] 650K->138K(1984K), 0.0002674 secs]
[GC [DefNew: 512K->0K(576K), 0.0002045 secs] 650K->138K(1984K), 0.0002796 secs]
[GC [DefNew: 512K->0K(576K), 0.0001704 secs] 650K->138K(1984K), 0.0002481 secs]
[GC [DefNew: 512K->0K(576K), 0.0002229 secs] 650K->138K(1984K), 0.0003118 secs]

Reproduced in both jdk1.5 and 1.6.

Can someone enlight me what's happening inside jvm (regarding class load and gc) ?

Thanks.

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