RFR: 8359110: Log accumulated GC and process CPU time upon VM exit [v9]

[Albert Mingkun Yang]

On Mon, 23 Jun 2025 13:12:28 GMT, Jonas Norlinder <duke at openjdk.org> wrote:

>> Add support to log CPU cost for GC during VM exit with `-Xlog:gc`.
>> 
>> 
>> [1.500s][info ][gc] GC CPU cost: 1.75%
>> 
>> 
>> Additionally, detailed information may be retrieved with `-Xlog:gc=trace`
>> 
>> 
>> [1.500s][trace][gc] Process CPU time: 4.945370s
>> [1.500s][trace][gc] GC CPU time: 0.086382s
>> [1.500s][info ][gc] GC CPU cost: 1.75%
>
> Jonas Norlinder has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 16 commits:
> 
>  - Remove incorrect is_gc_operation call after rebase
>  - More clean up, remove virtual
>  - Fixes after feedback from @stefank
>  - Remove extra whitespace
>  - operation_is_gc -> is_gc_operation per @stefank suggestion
>  - Only sample if needed
>  - Remove explicit super call and minor fixes
>  - Add CPU time tracking for string deduplication to log_gc_vtime
>  - Replace calls to log_gc_vtime with super-class method calls
>  - Add bug fix after refactor and fixes for review
>  - ... and 6 more: https://git.openjdk.org/jdk/compare/c748d358...553edc48

src/hotspot/share/gc/shared/collectedHeap.hpp line 245:

> 243: 
> 244:   // Stop any onging concurrent work and prepare for exit.
> 245:   virtual void stop();

I find it a bit odd to call `log_gc_vtime` inside this method, given the comment and its name. I wonder if `print_tracing_info` can be used instead, which is invoked before exit as well.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25779#discussion_r2161728711