RFR: 8361099: Shenandoah: Improve heap lock contention by using CAS for memory allocation [v20]

[Xiaolong Peng]

On Tue, 6 Jan 2026 00:32:24 GMT, Kelvin Nilsen <kdnilsen at openjdk.org> wrote:

>> Xiaolong Peng has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 265 commits:
>> 
>>  - Merge branch 'openjdk:master' into cas-alloc-1
>>  - Fix build error after merging from tip
>>  - Merge branch 'master' into cas-alloc-1
>>  - Merge branch 'master' into cas-alloc-1
>>  - Some comments updates as suggested in PR review
>>  - Fix build failure after merge
>>  - Expend promoted from ShenandoahOldCollectorAllocator
>>  - Merge branch 'master' into cas-alloc-1
>>  - Address PR comments
>>  - Merge branch 'openjdk:master' into cas-alloc-1
>>  - ... and 255 more: https://git.openjdk.org/jdk/compare/de81d389...cf13b7b5
>
> src/hotspot/share/gc/shenandoah/heuristics/shenandoahHeuristics.cpp line 102:
> 
>> 100:   for (size_t i = 0; i < num_regions; i++) {
>> 101:     ShenandoahHeapRegion* region = heap->get_region(i);
>> 102:     assert(!region->is_active_alloc_region(), "Not expecting any active alloc region at the time");
> 
> Same suggestion here as with shenandoahGenerationalHeuristics.cpp.

fixed

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PR Review Comment: https://git.openjdk.org/jdk/pull/26171#discussion_r2670313055