The 5.0 spec for runFinalization() says:
"Calling this method suggests that the Java Virtual Machine expend
effort toward running the finalize methods of objects that have been
found to be discarded but whose finalize methods have not yet been run."
and for gc():
"Calling the gc method suggests that the Java Virtual Machine expend
effort toward recycling unused objects"
The key word in both those specs is /suggests/. There is *no* guarantee
that any finalizers are run or that a gc actually occurs when these
calls are made - it is only a hint to the VM.
If a test is expecting these calls to definitely gc and run finalizers,
then IMO the test is in error.
Regards,
Oliver
Xiao-Feng Li wrote:
In classlib tests "gc.PhantomReferenceTest" and
"tests.api.java.lang.ref.ReferenceTest", they expect weakreference
objects be queued after System.runFinalization(). Is this correct? In
my understanding of the spec, there is no requirement on this
behavior.
The tests do like this:
=========================
//wr is the weakreference, whose referent is only weakly reachable.
//rq is the reference queue
System.gc();
System.runFinalization();
ref = rq.poll();
assertTrue("Unexpected ref2", ref == wr);
assertNotNull("Object not garbage collected.", ref);
assertNull("Object could not be reclaimed.", ref.get());
=========================
After runFinalization(), it requires the queue has the weakreference.
Actually it has requirement on System.gc() as well, requiring it to
identify the weakly reachable object accurately.
In my understanding of the spec, this kind of tests are wrong. It
forces the GC to do something not required by spec.
How do you think?
Thanks,
xiaofeng
--
Oliver Deakin
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