RFR: 8253064: monitor list simplifications and getting rid of TSM [v4]

[Daniel D.Daugherty]

On Tue, 10 Nov 2020 17:05:16 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Daniel D. Daugherty has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   dholmes-ora - convert inner while loop to do-while loop in unlink_deflated().
>
> src/hotspot/share/runtime/objectMonitor.cpp line 540:
> 
>> 538:     if (try_set_owner_from(NULL, DEFLATER_MARKER) != NULL) {
>> 539:       // The owner field is no longer NULL so we lost the race since the
>> 540:       // ObjectMonitor is now busy.
> 
> So here would contentions be > 0?  Can it be asserted?  Doesn't need to be, the comment really helps to understand why the cas failed.

No we can't assert that (contentions > 0). The ownership
might have been taken by a fast path thread so it grabbed
ownership without having to update contentions and wait.

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