[8u] RFR (S) 8227018: CompletableFuture should not call Runtime.availableProcessors on fast path

[Martin Buchholz]

Looks good to me.

Of course, this would benefit from our pending 8u jsr166 tck backport,
which includes exhaustive tests of CompletableFuture.

On Mon, Jul 1, 2019 at 8:08 AM Aleksey Shipilev <shade at redhat.com> wrote:

> RFE:
>   https://bugs.openjdk.java.net/browse/JDK-8227018
>
> 8u webrev:
>   http://cr.openjdk.java.net/~shade/8227018/webrev.01/
>
> In 8u, CompletableFuture calls Runtime.availableProcessors during spin in
> waitingGet. Unfortunately,
> that falls victim to JDK-8227006, which makes it too costly. This is fixed
> in 9 with JDK-8134851,
> but that patch is too large and intrusive to backport to 8u. Therefore, we
> should consider
> backporting the small part of that patch that deals with
> availableProcessors handling.
>
> Testing: "tier1"-like testing
>
> --
> Thanks,
> -Aleksey
>
>