RFR: 8258431: Provide a JFR event with live set size estimate [v9]

[Jaroslav Bachorik]

On Tue, 2 Mar 2021 17:34:32 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Jaroslav Bachorik has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add tests for the heap usage summary event
>
> src/hotspot/share/gc/shared/space.inline.hpp line 190:
> 
>> 188:         oop obj = oop(cur_obj);
>> 189:         size_t obj_size = obj->size();
>> 190:         compact_top = cp->space->forward(obj, obj_size, cp, compact_top);
> 
> This change seems superfluous now. Inline `obj_size` back?

Done

> src/hotspot/share/gc/shared/space.hpp line 555:
> 
>> 553:   size_t live() const            {
>> 554:     return used() - _dead_space;
>> 555:   }
> 
> Move it a few lines down, so `capacity`, `used`, `live` line up?

Ok. I did my best to make the code look nice there :)

> src/hotspot/share/gc/shared/collectedHeap.hpp line 218:
> 
>> 216:   virtual size_t capacity() const = 0;
>> 217:   virtual size_t used() const = 0;
>> 218:   // Returns the estimate of live set size. Because live set changes over time,
> 
> I believe a blank line is in order here, look at other comments in the same header.

Done

> src/hotspot/share/gc/shared/space.inline.hpp line 90:
> 
>> 88: 
>> 89: public:
>> 90:   size_t _dead_space;
> 
> Should this really be "public"? Maybe `friend`-ing with the only user is better?

Yep. Befriended.

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PR: https://git.openjdk.java.net/jdk/pull/2579