RFR: 8338977: Parallel: Improve heap resizing heuristics [v3]

[Albert Mingkun Yang]

On Mon, 30 Jun 2025 09:08:28 GMT, Ivan Walulya <iwalulya at openjdk.org> wrote:

>>> so that we can do the check after all the GCs
>> 
>> Well, not really. In the old impl, `GCOverheadChecker::check_gc_overhead_limit` calls `set_gc_overhead_limit_exceeded` only for full-gc.
>> 
>>  > But now you only use check_gc_overhead_limit in ParallelScavengeHeap::satisfy_failed_allocation. I suspect whether it can check the gc overhead limit accurately.
>> 
>> I believe so.  In the old impl, we don't check gc-overhead for explicit gcs. Only allocation-failure caused gcs are interesting, which all go through `satisfy_failed_allocation`.
>> 
>> 
>>   // Ignore explicit GC's.  Exiting here does not set the flag and
>>   // does not reset the count.
>>   if (GCCause::is_user_requested_gc(gc_cause) ||
>>       GCCause::is_serviceability_requested_gc(gc_cause)) {
>>     return;
>>   }
>
> `check_gc_overhead_limit` does more than `check`, can we find a more appropriate method name?

The only side-effect is mutating `_gc_overhead_counter`, which I believe is part of checking gc overhead limit. Do you have any names in mind?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25000#discussion_r2174712372