RFR: 8356698: JFR: @Contextual

[Erik Gahlin]

On Sat, 31 May 2025 18:58:29 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> Could I have a review of a new annotation that can be used to annotate a field as contextual. 
>> 
>> Testing: jdk/jdk/jfr + tier1
>> 
>> Thanks
>> Erik
>
> src/jdk.jfr/share/classes/jdk/jfr/events/MethodTraceEvent.java line 39:
> 
>> 37: public final class MethodTraceEvent extends AbstractJDKEvent {
>> 38: 
>> 39:     @Contextual
> 
> Should the MethodTraceEvent's method field really have this annotation? Or is it a remnant from testing?

I think it can be useful if a contextual GUI is created where users can drill down into tables and see all events that occur during a method call. For example, if you want to troubleshoot a slow login:

    $ java -XX:StartFlightRecording:method-trace=LoginService::login ...

| Context Types
|-----------------------------------
| Order::id
| **MethodTrace::method** (selected)
| Trace::span
| Trace::name                            

|Context Values
|-----------------------------------
| **LoginService::login(String, String)** (selected)


Start Time      | Event Type                   | Duration 
--------------|-----------------------|-------------
20:05:02.45   | jdk.JavaMonitorEnter  |  25 ms
 20:05:03.12  | jdbc.ExecuteQuery      |  2 s

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/25249#discussion_r2119629183