Threads should not be Cloneable

[David Holmes]

Florian Weimer said the following on 08/15/10 21:51:
> Classes storing native pointers must never be cloneable.  I hope
> having identified all such cases in the JDK, but I can post my scripts
> so that others can try to find more instances.

I would not say that "Classes storing native pointers must never be 
cloneable" - the same cloning considerations apply to a native pointer 
as they do a Java reference: does it make sense for two instances to 
share the same pointer/reference? If the answer is no then you need to 
define a custom clone() method if you want to be able to correctly clone 
a class.

The ability of a subclass to introduce cloning in a way that can use a 
broken superclass clone() implementation is also not in itself 
necessarily a security issue. You can only clone subclass instances, not 
arbitrary superclass instances - so it really comes down to the details 
of the class concerned.

David Holmes