> After the finalize method has been invoked for an object, <bold>no
> further action is taken until the Java virtual machine has again
> determined that there is no longer any means by which this object can
> be accessed by any thread that has not yet died, <bolder>including
> possible actions by other objects or classes which are ready to be
> finalized, at which point the object may be discarded.
> </bolder></bold>
>
>
> INCLUDING POSSIBLE ACTIONS BY OTHER OBJECTS OR CLASSES
> WHICH ARE READY TO BE FINALIZED
Note:
There's a difference between "discarded" and "finalized".
If you have two objects, A and B, and A references B, and both of them
are unreachable from the root set of references (i.e. both are eligible
for GC), then A and B may be *finalized* in any order.
However, B may not be *discarded* before A. That is, when A's finalize()
runs, B may already be finalized. But B must still exist - the reference
to B that A holds may not be an pointer into a random memory area that
used to contain B.
For the C++ people, B may have had its finalize() method run, but nobody
has
yet freed its memory.
So the JVM can do this:
1. Figure out all objects eligible for GC. ("garbage objects")
2. Run finalize() on them in any order.
3. Free the memory associated with them in any order.
Note that after step (2), no garbage object will do anything. Thus, the
garbage is
guaranteed to be "inert" - there will be no code that can possibly
access
these objects any more. A garbage object won't access another garbage
object, becuase they are all finalized. A non-garbage object won't
access
a garbage object, because if it could, the garbage object would not be
garbage.
/LS
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