[jdk16] RFR: 8258985: Parallel WeakProcessor may use too few threads [v2]

[Albert Mingkun Yang]

On Fri, 8 Jan 2021 12:45:12 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Lgtm although the comments in the documentation for both `static void weak_oops_do` method declarations mentions:
>> 
>>   // Parallel version.  Uses ergo_workers(), active workers, and
>>   // phase_time's max_threads to determine the number of threads to use.
>> which should be fixed.
>> 
>> One option is to put something like "Uses max workers and the total number of weak references to determine the number of threads to use" as description for `ergo_workers` and remove the details in the description of the `weak_oops_do` descriptions, but just removing the mention of `active_workers` there could be fine too.
>
> Thanks @tschatzl . I've updated the descriptions of the weak_oops_do functions, and also added a description for ergo_workers.

What's the argument for using `total_workers()` here? BTW, `G1ConcurrentMark::weak_refs_work` is in the caller chain. According to its name, it happens outside a pause.

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PR: https://git.openjdk.java.net/jdk16/pull/75