8017163: minor question regarding the calculation and logging of card set coarsening statistics

[Thomas Schatzl]

Hi,

On 17.05.22 16:38, Tianqi Xia wrote:
> Hi,
> 
> I continued to play around with JDK-8017163: G1: Refactor remembered sets,
> after going through the code, I was really amazed by the delicate magic of
> all those different card containers.
> 
> I ran BigRamTester with a 20GB heap for a couple minutes, observed the logs
> of coarsening statistics, and noticed the data displayed after "Coarsening
> (recent)" seems a little bit abnormal, here is what I mean:
> 

[...]

>  From the comments in code, "Coarsening (recent)" represents the number of
> coarsening happened during the lastest GC cycle, in my understanding it
> should be calculated by something like:
> 
> current total coarsening - previous total coarsening
> 
> However, after looking at G1CardSet::print_coarsen_stats) the recent
> coarsening stats are instead calculated by:
> 
> current total coarsening - coarsening happened in previous(the one before
> the latest) GC cycle
> 
> Am I missing something here?
> 

I filed https://bugs.openjdk.java.net/browse/JDK-8286893. Maybe you have 
time to look into this?

Thanks,
   Thomas