RFR: 8253064: monitor list simplifications and getting rid of TSM

[Daniel D.Daugherty]

On Fri, 6 Nov 2020 01:54:52 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Changes from @fisk and @dcubed-ojdk to:
>> 
>> - simplify ObjectMonitor list management
>> - get rid of Type-Stable Memory (TSM)
>> 
>> This change has been tested with Mach5 Tier[1-3],4,5,6,7,8; no new regressions.
>> Aurora Perf runs have also been done (DaCapo-h2, Quick Startup/Footprint,
>> SPECjbb2015-Tuned-G1, SPECjbb2015-Tuned-ParGC, Volano)
>>   - a few minor regressions (<= -0.24%)
>>   - Volano is 6.8% better
>> 
>> Eric C. has also done promotion perf runs on these bits and says "the results look fine".
>
> src/hotspot/share/runtime/monitorDeflationThread.hpp line 44:
> 
>> 42: 
>> 43:   // Hide this thread from external view.
>> 44:   bool is_hidden_from_external_view() const      { return true; }
> 
> Style nit: a single space after "const" suffices

Fixed.

I copied that from the serviceThread.hpp file, but, since I haven't otherwise
touched that file in this changeset, I'm going to leave serviceThread.hpp alone.

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PR: https://git.openjdk.java.net/jdk/pull/642