FULL PRODUCT VERSION :
java version "1.6.0_04"
Java(TM) SE Runtime Environment (build 1.6.0_04-b12)
Java HotSpot(TM) Client VM (build 10.0-b19, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Windows XP Professional Service Pack 2

A DESCRIPTION OF THE PROBLEM :
Attempting to cast a nonNumber object to Number results in a ClassCastException, which results in a sizeable memory leak if there is a high frequency of such exceptions,

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile and run the attached test program and monitor the Memory Usage using the Task Manager or Process Explorer. It will grow considerably using Java 6 (any release) or Java 7, but not with Java 5.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Both the Java heap and the overall memory usage snould remain constant, once the JVM is fully operational.
ACTUAL -
The memory size grows from 8mb to over 600mb when running the test program.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
None


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class TestMe {
  public static void main(String args[]) {
  long numExceptions = 0L;
  String str = "";
  Object o = str;
  for (int i = 0; i < 10000000; i++) {
   try {
    double x = ((Number)o).doubleValue();
   } catch (ClassCastException ex) {
    numExceptions++;
   }
  }
  System.out.println("numExceptions="+numExceptions);
 }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
public class TestMe {
  public static void main(String args[]) {
  long numExceptions = 0L;
  String str = "";
  Object o = str;
  for (int i = 0; i < 10000000; i++) {
   try {
    if (o instanceof Number) {
     double x = ((Number)o).doubleValue();
    }
   } catch (ClassCastException ex) {
    numExceptions++;
   }
  }
  System.out.println("numExceptions="+numExceptions);
 }
}

However, there may be other cases where Exception objects are being created for which sucn a workaround is not sufficient.

Release Regression From : 5.0u12
The above release value was the last known release where this
bug was not reproducible. Since then there has been a regression.