The use of annotation-valued annotation elements causes class loaders that
contain the annotation types to be retained. This results in a memory leak
and may prevent the use of annotations in some enterprise applications.

==========$ ls -la
total 28
drwxr-xr-x 2 gafter 4096 Apr 30 10:03 .
drwxr-xr-x 17 gafter 4096 Apr 29 22:33 ..
-rw-r--r-- 1 gafter 113 Apr 30 09:41 A.java
-rw-r--r-- 1 gafter 23 Apr 30 09:31 B.java
-rw-r--r-- 1 gafter 29 Apr 30 09:31 C.java
-rw-r--r-- 1 gafter 3001 Apr 30 09:44 Main.java
-rw-r--r-- 1 gafter 300 Apr 30 09:58 Makefile
==========$ for file in *; do echo //////////////////// $file ; cat -n $file; done
//////////////////// A.java
     1 public
     2 @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.RUNTIME)
     3 @interface A {
     4 B b();
     5 }
//////////////////// B.java
     1 public @interface B {}
//////////////////// C.java
     1 public @A(b=@B()) class C {}
//////////////////// Main.java
     1 import java.net.*;
     2 import java.lang.ref.*;
     3 import java.util.*;
     4 import java.io.*;
     5
     6 public class Main {
     7 public static void main(String[] args) throws Exception {
     8 for (int i=0; i<100; i++)
     9 doTest(args.length != 0);
    10 }
    11
    12 static void doTest(boolean readAnn) throws Exception {
    13 // URL classes = new URL("file://" + System.getProperty("user.dir") + "/classes");
    14 // URL[] path = { classes };
    15 // URLClassLoader loader = new URLClassLoader(path);
    16 ClassLoader loader = new SimpleClassLoader();
    17 WeakReference<Class<?>> c = new WeakReference(loader.loadClass("C"));
    18 if (c.get() == null) throw new AssertionError();
    19 if (c.get().getClassLoader() != loader) throw new AssertionError();
    20 if (readAnn) System.out.println(c.get().getAnnotations()[0]);
    21 if (c.get() == null) throw new AssertionError();
    22 System.gc();
    23 System.gc();
    24 if (c.get() == null) throw new AssertionError();
    25 System.gc();
    26 System.gc();
    27 loader = null;
    28 System.gc();
    29 System.gc();
    30 if (c.get() != null) throw new AssertionError();
    31 }
    32 }
    33
    34 class SimpleClassLoader extends ClassLoader {
    35 private Hashtable classes = new Hashtable();
    36
    37 public SimpleClassLoader() {
    38 }
    39 private byte getClassImplFromDataBase(String className)[] {
    40 byte result[];
    41 try {
    42 FileInputStream fi = new FileInputStream("classes/"+className+".class");
    43 result = new byte[fi.available()];
    44 fi.read(result);
    45 return result;
    46 } catch (Exception e) {
    47
    48 /*
    49 * If we caught an exception, either the class wasnt found or it
    50 * was unreadable by our process.
    51 */
    52 return null;
    53 }
    54 }
    55 public Class loadClass(String className) throws ClassNotFoundException {
    56 return (loadClass(className, true));
    57 }
    58 public synchronized Class loadClass(String className, boolean resolveIt)
    59 throws ClassNotFoundException {
    60 Class result;
    61 byte classData[];
    62
    63 /* Check our local cache of classes */
    64 result = (Class)classes.get(className);
    65 if (result != null) {
    66 return result;
    67 }
    68
    69 /* Check with the primordial class loader */
    70 try {
    71 result = super.findSystemClass(className);
    72 return result;
    73 } catch (ClassNotFoundException e) {
    74 }
    75
    76 /* Try to load it from our repository */
    77 classData = getClassImplFromDataBase(className);
    78 if (classData == null) {
    79 throw new ClassNotFoundException();
    80 }
    81
    82 /* Define it (parse the class file) */
    83 result = defineClass(classData, 0, classData.length);
    84 if (result == null) {
    85 throw new ClassFormatError();
    86 }
    87
    88 if (resolveIt) {
    89 resolveClass(result);
    90 }
    91
    92 classes.put(className, result);
    93 return result;
    94 }
    95 }
//////////////////// Makefile
     1 JAVAC=/java/re/j2se/1.5.0/promoted/beta2/b49/binaries/solaris-sparc/bin/javac
     2 JAVA=/java/re/j2se/1.5.0/promoted/beta2/b49/binaries/solaris-sparc/bin/java
     3
     4 all:
     5 mkdir -p classes
     6 $(JAVAC) -d classes A.java B.java C.java
     7 $(JAVAC) Main.java
     8 # this works
     9 $(JAVA) Main
    10 # this fails
    11 $(JAVA) Main foo
==========$ make
mkdir -p classes
/java/re/j2se/1.5.0/promoted/beta2/b49/binaries/solaris-sparc/bin/javac -d classes A.java B.java C.java
/java/re/j2se/1.5.0/promoted/beta2/b49/binaries/solaris-sparc/bin/javac Main.java
Note: Main.java uses or overrides a deprecated API.
/java/re/j2se/1.5.0/promoted/beta2/b49/binaries/solaris-sparc/bin/javac Main.java
Note: Main.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: Main.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
# this works
/java/re/j2se/1.5.0/promoted/beta2/b49/binaries/solaris-sparc/bin/java Main
# this fails
/java/re/j2se/1.5.0/promoted/beta2/b49/binaries/solaris-sparc/bin/java Main foo
@A(b=@B())
Exception in thread "main" java.lang.AssertionError
        at Main.doTest(Main.java:30)
        at Main.main(Main.java:9)
make: *** [all] Error 1
==========$