RFR: 8352738: Implement JEP 520: JFR Method Timing and Tracing

[Chen Liang]

On Mon, 19 May 2025 15:24:42 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

> Could I have a review of this enhancement that will add tracing capabilities to JFR? There are opportunities for performance improvements in the implementation, but I would rather add them later and separately.
> 
> Testing: tier 1-3, test/jdk/jdk/jfr
> 
> Thanks
> Erik

Mainly looked at bytecode transformation; those look good.

src/jdk.jfr/share/classes/jdk/jfr/internal/JDKEvents.java line 81:

> 79:         InitialSecurityPropertyEvent.class,
> 80:         MethodTraceEvent.class,
> 81:         MethodTimingEvent.class

Suggestion:

        MethodTimingEvent.class,

for future additions.

src/jdk.jfr/share/classes/jdk/jfr/internal/LogTag.java line 104:

> 102:      *  Covers usage of MethodTiming and MethodTrace events
> 103:      */
> 104:     JFR_METHODTRACE(16);

You can consider adding a trailing `,` and moving `;` onto a new line if addition to this enum is frequent.

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PR Review: https://git.openjdk.org/jdk/pull/25306#pullrequestreview-2862226134
PR Review Comment: https://git.openjdk.org/jdk/pull/25306#discussion_r2103182014
PR Review Comment: https://git.openjdk.org/jdk/pull/25306#discussion_r2103184030