RFR: 8367982: Unify ObjectSynchronizer and LightweightSynchronizer [v2]

[Fredrik Bredberg]

On Mon, 27 Oct 2025 00:20:19 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Fredrik Bredberg has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update after review
>
> src/hotspot/share/runtime/synchronizer.cpp line 287:
> 
>> 285:   _last_async_deflation_time_ns = os::javaTimeNanos();
>> 286: 
>> 287:   ObjectSynchronizer::create_om_table();
> 
> The original code should effectively be inlined here:
> 
> if (UseObjectMonitorTable) {
>   ObjectMonitorTable::create();
> }

Tried to do a quick fix for this, but `ObjectMonitorTable` is not known at this point, and forward declaring it turned out to be a mess. So, since we agreed to move out `ObjectMonitorTable` to a separate file, I think this can be postponed until that file has been created.

> src/hotspot/share/runtime/synchronizer.cpp line 1838:
> 
>> 1836:   if (!UseObjectMonitorTable) {
>> 1837:     return;
>> 1838:   }
> 
> This should move to the caller and be replaced with an assertion at this level. Though you don't need to introduce this method at all as the caller can call `OMT::create` directly.

Same as last answer, this is easily done once we have moved `ObjectMonitorTable` to a separate file, but not until then.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27915#discussion_r2481507181
PR Review Comment: https://git.openjdk.org/jdk/pull/27915#discussion_r2481511224