RFR: 8203359: Container level resources events [v9]

[Jaroslav Bachorik]

On Wed, 21 Apr 2021 22:38:32 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

>> Jaroslav Bachorik has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix event metadata
>
> I wonder if something similar to below could be added to jdk.jfr.internal.Utils:
> 
>     private static Metrics[] metrics;
>     public static Metrics getMetrics() {
>         if (metrics == null) {
>             metrics = new Metrics[] { Metrics.systemMetrics() };
>         }
>         return metrics[0];
>     }
> 
>     public static boolean shouldSkipBytecode(String eventName, Class<?> superClass) {
>         if (superClass != AbstractJDKEvent.class) {
>             return false;
>         }
>         if (!eventName.startsWith("jdk.Container")) {
>             return false;
>         }
>         return getMetrics() == null;
>     }
> 
> Then we could add checks to jdk.jfr.internal.JVMUpcalls::bytesForEagerInstrumentation(...)
> 
>     eventName = ei.getEventName();
>     if (Utils.shouldSkipBytecode(eventName, superClass))) {
>         return oldBytes;
>     }
> 
> and jdk.jfr.internal.JVMUpcalls:onRetransform(...)
> 
>     if (jdk.internal.event.Event.class.isAssignableFrom(clazz) && !Modifier.isAbstract(clazz.getModifiers())) {
>         if (Utils.shouldSkipBytecode(clazz.getName(), clazz.getSuperclass())) {
>             return oldBytes;
>         }
> 
> This way we would not pay for generating bytecode for events in a non-container environment. 
> 
> Not sure if it works, but could perhaps make startup faster? We would still pay for generating the event handlers during registration, but it's much trickier to avoid since we need to store the event type somewhere.

@egahlin Sounds good.
Any particular reason you are using `Metrics[]` array?

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

PR: https://git.openjdk.java.net/jdk/pull/3126