RFR: 8307488: Incorrect weight of the first ObjectAllocationSample JFR event [v2]

[Aleksey Shipilev]

On Fri, 26 May 2023 11:05:22 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> Greetings,
>> 
>> this PR fixes the problem with incorrect weights attribution for the initial ObjectAllocationSample event.
>> 
>> Testing: jdk_jfr
>> 
>> Thanks
>> Markus
>
> Markus Grönlund has updated the pull request incrementally with one additional commit since the last revision:
> 
>   variable rename

src/hotspot/share/jfr/recorder/service/jfrRecorderService.cpp line 146:

> 144:   iterate(jit, coas);
> 145:   JfrNonJavaThreadIterator njit;
> 146:   iterate(njit, coas);

Apologies for the post-integration review, but I have a question/suggestion. This code retains the JavaThread iterator while NonJavaThreadIterator is running, which feels unnecessary. Also, if we have thousands of threads, walking these threads and doing the unconditional `clear_last_allocated_bytes` there seems redundant and heavy-weight if the relevant JFR event is off.

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PR Review Comment: https://git.openjdk.org/jdk/pull/14158#discussion_r1210007990