RFR: 8284161: Implementation of Virtual Threads (Preview) [v8]

[Mikhailo Seledtsov]

On Wed, 27 Apr 2022 14:24:20 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> This is the implementation of JEP 425: Virtual Threads (Preview).
>> 
>> We will refresh this PR periodically to pick up changes and fixes from the loom repo.
>> 
>> Most of the new mechanisms in the HotSpot VM are disabled by default and require running with `--enable-preview` to enable.
>> 
>> The patch has support for x64 and aarch64 on the usual operating systems (Linux, macOS, and Windows). There are stubs (calling _Unimplemented_) for zero and some of the other ports. Additional ports can be contributed via PRs against the fibers branch in the loom repo.
>> 
>> There are changes in many areas. To reduce notifications/mails, the labels have been trimmed down for now to hotspot, serviceability and core-libs. We'll add the complete set of labels when the PR is further along.
>> 
>> The changes include a refresh of java.util.concurrent and ForkJoinPool from Doug Lea's CVS. These changes will probably be proposed and integrated in advance of this PR.
>> 
>> The changes include some non-exposed and low-level infrastructure to support the (in draft) JEPs for Structured Concurrency and Extent Locals. This is to make life a bit easier and avoid having to separate VM changes and juggle branches at this time.
>
> Alan Bateman has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Refresh 7965cc6b168e567ac2596f2fbc3b00a7d99b7e1e

I have reviewed the following portions of this change: 
  test/common, test/gtest, test/hotspot/runtime, test/jdk/jfr, test library

Feedback:
  - see several minor comments inline
  - under runtime/cds/appcds/test-classes there is an empty "TEST.properties" file; was it added by mistake?

With only a few minor comments, I approve of the code reviewed by me provided that my comments will be addressed.

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PR: https://git.openjdk.java.net/jdk/pull/8166