RFR: 8336463: Parallel: Add PSOldGen::expand_and_allocate

[Albert Mingkun Yang]

On Tue, 16 Jul 2024 13:00:23 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

>> Simple adding an API to old-gen to support calls by VM thread in safepoint.
>> 
>> Test: tier1-3
>
> src/hotspot/share/gc/parallel/psOldGen.cpp line 129:
> 
>> 127:     expand(word_size*HeapWordSize);
>> 128:   }
>> 129:   return cas_allocate_noexpand(word_size);
> 
> This implies a race and `cas_allocate_noexpand()` can fail prematurely due to the race. Is it an acceptable case?

Can you elaborate what are racing here?

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PR Review Comment: https://git.openjdk.org/jdk/pull/20189#discussion_r1679458048