[crac] RFR: Resize ForkJoinPool and some concurrent data structures

[Radim Vansa]

On Fri, 24 Mar 2023 15:36:30 GMT, Ashutosh Mehra <duke at openjdk.org> wrote:

>> Some parts of JDK expect that #cpus is constant; update those places after restore.
>
> Reading up the discussion on [FJP::setParallelism](https://mail.openjdk.org/pipermail/crac-dev/2022-May/000229.html), it was suggested [here](https://mail.openjdk.org/pipermail/crac-dev/2022-May/000230.html) to have crac branch receiving updates from openjdk/jdk/master, and crac-17u from openjdk/jdk17u/master. 
> 
> If we go with that plan, then this PR can be targeted to crac-17u while the crac branch can make use of Doug's patch.
> Although it would fragment the implementation across the two branches, but as long as they are providing the same functionality, I guess we can live with that. Does that make sense?

@ashu-mehra that was my intention; I expect these changes to be overwritten when main crac rebases to later JDK, and keep them only in crac-17u.

@DanHeidinga I would expect this kind of reaction for 17 as well, but since I am not so positive in maintaining them in CRaC I went rather for this independent PR. There won't be a perfect solution; let's see what other stakeholders would have to say.

-------------

PR Comment: https://git.openjdk.org/crac/pull/54#issuecomment-1483109437