RFR: 8253064: monitor list simplifications and getting rid of TSM [v5]

[Daniel D.Daugherty]

On Tue, 10 Nov 2020 21:16:33 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> So if I narrow the scope around the ThreadBlockInVM, then it would be fine?
>> 
>> {
>>   // Honor block request.
>>   ThreadBlockInVM tbivm(self);
>> }
>> 
>> I can make that change before I integrate...
>
> Yes that avoids it!

Done. I also did the one in ObjectSynchronizer::request_deflate_idle_monitors().

>> What does this "you can do this entire loop while blocked instead" mean?
>> 
>> Releasing during deflation kind of messes with the life-cycle I was trying
>> to enforce since deletion is the nature end-of-life for these... But to think
>> about that I need to know what you mean by "you can do this entire loop
>> while blocked instead"...
>
> If you only need to free CHeap memory, you can do:
>    size_t deleted_count = 0;
>    ThreadBlockInVM tbivm(self);
>     for (ObjectMonitor* monitor: delete_list) {
>       delete monitor;
>       deleted_count++;
>     }
>   }

Ahhh... but that only works if we release the oopStorage when
we deflate. Okay. I grok it now, but don't want to do that in this
changeset. I would want a complete stress test cycle for that
kind of a change.

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