RFR: 8170067: -XX:ExplicitGCInvokesConcurrentAndUnloadsClasses is not implemented for G1

[sangheon]

Hi Erik,

On 11/23/2016 05:05 AM, Erik Helin wrote:
> Hi all,
>
> I just added support for 
> -XX:ExplicitGCInvokesConcurrentAndUnloadsClasses in G1. Since G1 
> already unloads classes after a concurrent mark by default, I just 
> made -XX:+ExplicitGCInvokesConcurrentAndUnloadsClasses enable 
> -XX:+ExplicitGCInvokesConcurrent. I also added a constraint function 
> to check for some bad flag combinations and a corresponding test.
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8170067
>
> Webrev:
> http://cr.openjdk.java.net/~ehelin/8170067/00/
Actually I was thinking about the combination of 3 flags(similar to 
ExplicitGCInvokesConcurrentAndUnloadsClasses = 
ExplicitGCInvokesConcurrent + ClassUnloadingWithConcurrentMark). And for 
the constraint of ExplicitGCInvokesConcurrentAndUnloadsClasses, I think 
we are missing -ExplicitGCInvokesConcurrentAndUnloadsClasses / 
+ExplicitGCInvokesConcurrent / +ClassUnloadingWithConcurrentMark case 
(as Kim already mentioned).
As the default value of ExplicitGCInvokesConcurrentAndUnloadsClasses is 
false, we would need to add constraint functions for other 2 flags to 
check this combination.
-(by default)ExplicitGCInvokesConcurrentAndUnloadsClasses / 
+ExplicitGCInvokesConcurrent / +ClassUnloadingWithConcurrentMark

Thanks,
Sangheon

>
> Testing:
> - JPRT
> - New jtreg test
>
> Thanks,
> Erik