Integrated: 8321270: Virtual Thread.yield consumes parking permit

[Alan Bateman]

On Mon, 4 Dec 2023 16:08:32 GMT, Alan Bateman <alanb at openjdk.org> wrote:

> When a virtual thread continues after Thread.yield it currently consumes thread's parking permit. This is an oversight, the parking permit should only be consumed when continuing after park.
> 
> The changes are straight-forward. The internal "RUNNABLE" state is replaced with UNPARKED and YIELDED state, effectively encoding the previous state. So for the most part, it's just replacing the usages of RUNNABLE. The additional states require refactoring tryGetStackTrace, this is the method that is used for Thread::getStackTrace when the virtual thread is unmounted. It is also changed to not not swallow the REE if the reesubmit fails (tryStackTrace has to resubmit as the task for the thread may run, or the thread unparked, while "suspended" and sampling its stack trace). The changes are a subset of larger changes in the loom repo, future PRs will propose to bring in other changes to get main line up to date.
> 
> For testing the existing ThreadAPI has new test cases.
> 
> Testing: test1-5. This includes the JVMTI tests as it maps the thread states to JVMTI thread states.

This pull request has now been integrated.

Changeset: 29d7a223
Author:    Alan Bateman <alanb at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/29d7a22348e43cba253d0483c4c05922368f6b8a
Stats:     158 lines in 4 files changed: 79 ins; 19 del; 60 mod

8321270: Virtual Thread.yield consumes parking permit

Reviewed-by: sspitsyn

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PR: https://git.openjdk.org/jdk/pull/16953