RFR: 8321242: Enable WorkerThreads to run tasks in caller thread [v2]

[Stefan Karlsson]

On Tue, 5 Dec 2023 10:01:28 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> src/hotspot/share/gc/shared/workerThread.cpp line 49:
>> 
>>> 47:   // No workers are allowed to read the state variables until they have been signaled.
>>> 48:   _task = task;
>>> 49:   _not_finished = num_worker_tasks;
>> 
>> [preexisting] The assignment of _not_finished should be done with an Atomic::store.
>
> Amended.

Why should this be using Atomic::store? Concurrent accesses are guarded by the semaphores. That's what the comment tries to convene:

// No workers are allowed to read the state variables until they have been signaled.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16945#discussion_r1416919541