RFR: 8231672: Simplify the reference processing parallelization framework [v2]

[Leo Korinth]

On Thu, 4 Mar 2021 09:48:38 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Leo Korinth has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Changes after first review
>
>> I use references in some places where they can replace pointers. I could go much further here, but I did not
>> want to bloat the pull request, maybe later change all closures to be references as well? Should I create 
>> enhancements for this?
> 
> If necessary, generally do such changes (vs. the reference processing refactoring) in extra CRs. Changing pointers to references seems completely unrelated.
> 
> Fwiw, my personal opinion is to not do that at all for code that has lots of connections with existing code as this results in an awkward mixture in these areas between old an new code which only makes things hard to read (and adds another question when interfacing that code, do I need a reference or a pointer now?), but others may have other opinions.
> Also it generally hides the information at the call site whether something is actually passed as reference or as value (at least for classes/structs). Of course, as usual there is no hard rule, and I am good if others think it's the way to go.

I have tried to fix the formatting mess (sorry) and renaming of classes. I hope this looks better.

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PR: https://git.openjdk.java.net/jdk/pull/2782