RFR: 8306647: Implementation of Structured Concurrency (Preview) [v2]

[Rémi Forax]

On Thu, 25 May 2023 08:21:39 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> This is the implementation of:
>> 
>> - JEP 453: Structured Concurrency (Preview)
>> - JEP 446: Scoped Values (Preview)
>> 
>> For the most part, this is just moving code and tests.  StructuredTaskScope moves to j.u.concurrent as a preview API, ScopedValue moves to j.lang as a preview API, and module jdk.incubator.concurrent has been removed. The significant API changes since incubator are:
>> 
>> - StructuredTaskScope.fork returns Subtask instead of Future (JEP 453 has a section on this)
>> - ScopedValue.where methods are replaced with runWhere, callWhere and getWhere
>
> Alan Bateman has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 12 commits:
> 
>  - Sync up from loom repo
>  - Remove csm.Threads
>  - Merge
>  - Test should not be in update for main line
>  - Sync with loom repo
>  - Sync up tests frmo loom repo
>  - Sync up with loom repo
>  - Sync update API/impl/tests
>  - Merge
>  - Sync up with loom repo
>  - ... and 2 more: https://git.openjdk.org/jdk/compare/89f2d458...e92ba524

I've rewritten all my tests to use the new API, it works !
https://github.com/forax/loom-fiber/tree/java21

One surprising thing is that Subtask.get() give less leeway to the owner thread than to the other virtual threads so in onComplete() storing a Subtask to use it later by the owner thread does not work well if join() is not called yet.
This is perhaps a bit too much.

Anyway, good for me !

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PR Comment: https://git.openjdk.org/jdk/pull/13932#issuecomment-1568813363