RFR: 8301229: Clean up SuspendibleThreadSet::_suspend_all

[Thomas Schatzl]

On Fri, 27 Jan 2023 14:21:21 GMT, Erik Österlund <eosterlund at openjdk.org> wrote:

> The SuspendibleThreadSet::_suspend_all variable is read and set concurrently, yet relies only on volatiles in accessors. They should use Atomic instead. Also, the _suspend_all getter is called suspend_all(), but since this function doesn't suspend anything, the name looks really confusing where it is, and there is an alias should_yield() that just calls suspend_all(), and better explains what the code does. This CR aims to remove suspend_all() and have a single getter, being should_yield (which reads better everywhere it is used), and make sure the accessors do use Atomic.

Marked as reviewed by tschatzl (Reviewer).

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PR: https://git.openjdk.org/jdk/pull/12256