RFR: 8351594: JFR: Rate-limited sampling of Java events [v3]

[Markus Grönlund]

On Tue, 3 Jun 2025 12:50:49 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

>> Could I have review of an enhancement that adds rate-limited sampling to Java events, including five events in the JDK (SocketRead, SocketWrite, FileRead, FileWrite, and JavaExceptionThrow).
>> 
>> Testing: test/jdk/jdk/jfr
>> 
>> Thanks
>> Erik
>
> Erik Gahlin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix adjust boundary

Great stuff.

We have now what amounts to a carbon-copy of the existing throttling implementation used in the JVM, mainly used by the jdk.ObjectAllocationSample event. (see hotspot/src/share/jfr/support/jfrAdaptiveSampler.cpp and hotspot/src/share/jfr/recorder/service/jfrEventThrottler.cpp).

Smart work to write the Java implementation as a method-to-method comparison, which made it easier to review.

Thanks
Markus

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Marked as reviewed by mgronlun (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25559#pullrequestreview-2892579207