RFR: 8320304: Refactor and simplify monitor deflation functions [v4]

[Stefan Karlsson]

On Mon, 20 Nov 2023 23:12:17 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

>> The recent rewrites to remove safepointed monitor deflation allows us to simplify the monitor deflation code a bit. The code is now guaranteed to be called from the MonitorDeflationThread, which is a JavaThread, and never from the VMThread.
>> 
>> I would like to propose two changes to the code:
>> 1) Remove all code that supports monitor deflation from other threads than the MonitorDeflationThread
>> 2) Extract out the logging code so that it is easier to see the structure of the monitor deflation code
>> 
>> I have run minimal manual of this patch. I'd like to get some feedback on the proposal before I proceed to run more in-depth testing.
>
> Stefan Karlsson has updated the pull request incrementally with one additional commit since the last revision:
> 
>   David's review comments

Tier1-3 passed except
 * an unrelated failure in DNS test
 * macos x64 because of lack of available agents
Tier4-6 Linux-x64[-debug] passed

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PR Comment: https://git.openjdk.org/jdk/pull/16706#issuecomment-1822228539