Re: JavaMemoryModel: Use-case for strong volatile

From: Bill Pugh (pugh@cs.umd.edu)
Date: Thu Apr 08 2004 - 08:41:03 EDT


I'll admit that I am conflicted with regard to the strong vs. weak
interpretation. If we had really worked this out 5 months ago, I'd be
much more open to considering a change.

The problem is that the strong interpretation has been documented in
both the community review document and the public review document.
There have also been previous postings in which coding idioms where
recommended that only work under the strong interpretation (for the
optimistic readers pattern, which deliberating uses data races and
detects and recovers when a data race occurs).

In order to change something that was described in both the community
review and public review documents needs a pretty strong justification.
And I'm not convinced we have one.

        Bill

On Apr 7, 2004, at 8:22 PM, Sylvia Else wrote:

> At 02:14 AM 3/04/2004 -0600, Sarita Adve wrote:
>
>> I believe we can prove that the class of programs that are
>> data-race-free is
>> identical for the strong and weak semantics.
>
> If this is the case, then it should be final nail in the coffin for
> the strong interpretation.
>
> a) The model makes few positive guarantees for programs with data
> races making it very difficult to predict what the program will do.
> The model is primarily about saying what a program with data races
> will NOT do.
>
> b) The strong interpretation can complicate distributed
> implementations which compromises their efficiency for data race free
> programs.
>
> So where now is the justification for going with the strong
> interpretation?
>
> Sylvia.
>
>
>
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