[concurrency-interest] jdk9 VarHandle and Fence methods

Doug Lea dl at cs.oswego.edu
Sat Aug 22 09:58:30 EDT 2015


On 08/22/2015 09:06 AM, thurstonn wrote:
> I have a couple of questions, but first I wanted to make sure that I'm not
> missing something basic.
>
> This sentence:
> "We are NOT planning a full JMM memory model update for jdk9"
>
> should *not *be taken to mean that (for jdk9),
> <code>
> T getVolatile(Object owner) and
> T getAcquire(Object owner)
> </code>
> have the exact same "memory order effects", right?

Yes and no. They currently have the same implementation, and
any future changes will be compatible with this, but future
specs need not be identical. Although probably they will differ
at most in uninteresting ways, for example any wording needed to
continue to allow volatile fields that never escape threads to
be treated (essentially) as if non-volatile.

-Doug



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