RFR: 8280832: Update usage docs for NonblockingQueue

[David Holmes]

On Tue, 8 Feb 2022 22:58:26 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> Please review this update of the usage and implementation comments for
> NonblockingQueue to discuss the ABA issue in push/append operations.

src/hotspot/share/utilities/nonblockingQueue.inline.hpp line 122:

> 120:     // try_pop could take old_tail before our update, it gets recycled and
> 121:     // re-added to the end, and then we successfully cmpxchg, rendering the
> 122:     // list in _tail circular.

Doesn't this contradict the "We won any races with try_pop ... so we're done"!

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PR: https://git.openjdk.java.net/jdk/pull/7393