RFR: 8315884: New Object to ObjectMonitor mapping [v9]

[Coleen Phillimore]

On Wed, 17 Jul 2024 06:40:31 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> src/hotspot/share/runtime/basicLock.hpp line 46:
>> 
>>> 44:   // Used as a cache the ObjectMonitor* used when locking. Must either
>>> 45:   // be nullptr or the ObjectMonitor* used when locking.
>>> 46:   volatile uintptr_t _metadata;
>> 
>> The displaced header/markword terminology was very well known to people, whereas "metadata" is really abstract - people will always need to go and find out what it actually refers to. Could we not define a union here to support the legacy and lightweight modes more explicitly and keep the existing terminology for the setters/getters for the code that uses it?
>
> I should have read ahead. I see you do keep the setters/getters.

When we remove legacy locking in a couple of releases, we could rename this field cached_monitor.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20067#discussion_r1688015247