[GR-71287] Reduce JFR RSS contribution by substituting method tracing and timing classes

[roberttoyonaga]

JEP 520 introduced JFR method tracing and timing. This is a feature we do not support yet because it involves significant changes in Hotspot. If we substitute related classes we can reduce code size and image heap.

Using a basic Quarkus quickstart app this change results in a 0.92 MB code size decrease and a 1.31 MB image heap size decrease.

Before

After

I see a similar reduction when using a simple hello world app:

Before

After

If a user tries to use JFR method tracing and timing from the command line they will receive a warning log then JFR will continue working as normal:

$  ./simplebusywait -XX:StartFlightRecording=filename=rec.jfr,method-timing=::java.util.HashMap::resize
[warn][jfr,start] The .jfc option/setting 'method-timing' doesn't exist or is not supported.

If they try to use method tracing and timing by using a JFR configuration file (.jfc) instead, they will also get a warning:

$ ./simplebusywait -XX:StartFlightRecording=filename=rec.jfr,settings=custom.jfc
[warn][jfr,setting] Method timing and tracing is not supported yet.

[christianhaeubl]

Thanks, your PR should get integrated in the next few days.

[roberttoyonaga]

@christianhaeubl Can this be backported to the GraalVM for JDK 25 branch? I can open the backport request if you agree.

[christianhaeubl]

Should be safe to backport, feel free to open a the backport request.