RFR: 8342382: Implementation of JEP G1: Improve Application Throughput with a More Efficient Write-Barrier [v2]

[Thomas Schatzl]

On Thu, 27 Feb 2025 12:07:29 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   * remove unnecessarily added logging
>
> src/hotspot/share/gc/g1/g1ConcurrentRefine.cpp line 349:
> 
>> 347: 
>> 348:     bool do_heap_region(G1HeapRegion* r) override {
>> 349:       if (!r->is_free()) {
> 
> I am a bit lost on this closure; the intention seems to set unclaimed to all non-free regions, why can't this be done in one go, instead of first setting all regions to claimed (`reset_all_claims_to_claimed`), then set non-free ones unclaimed?

`do_heap_region()` only visits committed regions in this case. I wanted to avoid the additional check in the iteration code. If you still think it is more clear to filter those out later, please tell me. I'll add a comment for now.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23739#discussion_r1975250646