RFR [9] 8140687: Move @Contended to the jdk.internal.vm.annotation package

[Doug Lea]

On 11/11/2015 09:07 AM, Chris Hegarty wrote:

> So I think the questions we need to answer are as follows:
>   a) Is it desirable to have @Contended as part of Java SE?
>      i) If so, is this doable for JDK 9?
>   b) If ‘No’ to a or i, do we consider @Contended “critical”,
>        as per JEP 260 ?
>

@Contended is something that only a very small number of developers
directly use (sparingly), but the products of their efforts are used
by many other developers.

The "very small number" is still greater than the number of
java.util.concurrent maintainers. As the use of concurrency expands,
java.util.concurrent itself can't (and shouldn't) supply all possible
specialized components needed in applications, so external libraries
are needed to fill in the gaps. I'm sure that every developer of such
concurrent components would vote to be able to use @Contended.

I don't know of any argument not to expose it, beyond the usual
concerns about supporting nichy esoteric stuff in jdk. Under the
Unsafe-phase-out plans, public support for nichy esoteric stuff
that has no other functional alternative will be more common.

Without some good argument against it, I think the only issue
is where (what package) to place it. Carrying it out from there seems
identical to your webrev diffs, just changing import statements
and the like.


-Doug