RFR: 8330051: Small ObjectMonitor spinning code cleanups [v2]

[Coleen Phillimore]

On Wed, 17 Apr 2024 12:11:15 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> src/hotspot/share/runtime/objectMonitor.cpp line 395:
>> 
>>> 393:   // transitions.  The following spin is strictly optional ...
>>> 394:   // Note that if we acquire the monitor from an initial spin
>>> 395:   // we forgo posting JVMTI events and firing DTRACE probes.
>> 
>> This has always bothered me, but is existing and unrelated to your PR.
>
> I had some logging in one version of this patch and this call to TrySpin, succeeded a greater percentage of time, vs. the other calls to TrySpin.

<img width="396" alt="image" src="https://github.com/openjdk/jdk/assets/61806773/3e4d8801-c095-453b-86b1-926b2bef508f">

Here was my logging spreadsheet for interest.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18730#discussion_r1568764042