Re: JavaMemoryModel: Thread model algorithm.

From: Doug Lea (dl@cs.oswego.edu)
Date: Fri Nov 21 2003 - 07:38:42 EST


> If the specification allows the release and re-acquisition of the lock,
> this is certainly true. No test could demonstrate that the lock is not in
> fact released.
>
> On the other hand, if the specification prohibits the release and
> re-acquisition, then a single detection of a release would serve as a
> demonstration that the implementation is incorrect.
>
> What I find unsatisfactory is that the specification seems to be entirely
> silent on this issue, which creates the danger that people will, perhaps
> unconsciously, form improper inferences based on other aspects of the
> specification.
>
> I have no view on whether release and re-acquisition should be permitted
> (as distinct from mandated), but I think the specification should make it
> clear, one way or the other.
>

Sorry for not looking at the current JSR133 draft spec before writing
previous note. It explicitly prohibits release. Which seems
acceptable to all of us.

See page 30 of "Updated JSR-133 Community Review Document" at
  http://www.cs.umd.edu/~pugh/java/memoryModel/

-Doug
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