RFR: 8253064: monitor list simplifications and getting rid of TSM [v2]

[Daniel D.Daugherty]

On Mon, 9 Nov 2020 08:34:56 GMT, Erik Österlund <eosterlund at openjdk.org> wrote:

>> I noticed that in my preliminary review of Erik's changes. He checked
>> with the JFR guys and they said it just needed to be an address and
>> does not have to refer to the Object.
>> 
>> @fisk - can you think of a comment we should add here?
>
> We could write something along the lines of "An address that is 'unique enough', such that events close in time and with the same address are likely (but not guaranteed) to belong to the same object". This uniqueness property has always been more of a heuristic thing than anything else, as deflation shuffles the addresses around. Taking the this pointer vs an offset into the this pointer does however serve the exact same purpose; there was never any correlation to the contents of the object field.

Thanks @fisk! I've added a slightly edited version of the comment:
    // Set an address that is 'unique enough', such that events close in
    // time and with the same address are likely (but not guaranteed) to
    // belong to the same object.
@dholmes-ora - does this work for you?

>> I noticed that in my preliminary review of Erik's changes. He checked
>> with the JFR guys and they said it just needed to be an address and
>> does not have to refer to the Object.
>> 
>> @fisk - can you think of a comment we should add here?
>
> I wrote one in the section above, hope it is useful.

Thanks @fisk. I copied the same comment here since it is about
1000 lines away from the other comment.

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