RE: JavaMemoryModel: RE: Question on memory models

From: David Holmes (
Date: Thu Jul 01 1999 - 23:20:23 EDT

> Consider a static field Foo.x of type Object. In thread 1, you invoke
> Foo.x.toString(). Foo.x might reference an object of a class that has
> been loaded since the last time thread 1 did a memory barrier. So you
> can't easily tell if the vtbl entries are guaranteed to be valid.

Right - sorry about that half-baked scheme.

The point being made (which I failed to pick up) is that, just as
stale/garbage values for Java level fields could be read, so too
stale/garbage values for 'C' level object data could be read. Both need to
be fixed. Though I'd argue that the latter needs to be fixed even if we
decide the former need not - the VM should never crash due to an
application error. On the other hand if the VM is fixed then the Java level
fix will probably occur as a natural consequence.


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