FRF: Wiring GC events to JFR

[Zhengyu Gu]

On 08/27/2018 10:56 AM, Aleksey Shipilev wrote:
> On 08/27/2018 04:28 PM, Zhengyu Gu wrote:
>> http://cr.openjdk.java.net/~zgu/shenandoah/gc_messages/webrev.00/
> 
> This looks okay-ish. I would probably try and make a macro-generator for those strings, but current
> version is good enough for now.
> 
>> http://cr.openjdk.java.net/~zgu/shenandoah/jfr-event-1/webrev.00/
> 
> *) The introduction of GCTraceConcTime means it changes our logging, right? For example, it would
> print "Concurrent marking" without "gc+start", right? This is inconvenient and makes the logs noisy.
> Why do we need that change?

Well, GCTraceTime counts as pause time, that will distort the pause time 
displayed in JMC.


> 
> *) The comment is oddly formatted, and it seems "JMC" -> "JFR" is in order? Suggestion:
> 
>     // FIXME: It seems that JFR throws away level 0 events, which are the Shenandoah
>     // pause events. Create this pseudo level 0 event to push real events to level 1

JFR actually sends level 0 events, but are dropped by JMC.

Thanks,

-Zhengyu

> 
> Thanks,
> -Aleksey
>