RFR: 7902982: jcstress: Add samples for some mutex algorithms [v10]

[Aleksey Shipilev]

On Tue, 29 Jun 2021 20:35:15 GMT, mmirwaldt for openjdk <github.com+86246875+mmirwaldt-openjdk at openjdk.org> wrote:

> Wouldn't it make sense if the mutex algorithms call Thread.onSpinWait() instead of busy waiting?

It does not matter all that much here. Yes, it would be a little problematic when the tests are running on adjacent hyper-threads, but that is a minor problem. When running on separate cores, the harness would affine actors to their own cores, so spin-loop would not be problematic. If you do `Thread.onSpinWait` in this sample, you would not be able to run in with JDK 8. So, on balance, leaving it out is good.

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PR: https://git.openjdk.java.net/jcstress/pull/85