RFR (S) 8252043: Move inner class metaspace cleaning out of safepoint cleanup tasks

[Patricio Chilano]

Hi Coleen,

Changes look good to me.
I think you could have also just checked for 
SafepointSynchronize::is_at_safepoint() in ClassLoaderDataGraph::purge() 
instead of having the caller figure it out. I see that for all the 
current callers the value is always constant though so you save that 
check I guess.

Thanks,
Patricio
On 8/19/20 6:47 PM, Coleen Phillimore wrote:
> Summary: Clean up inner metaspaces from ServiceThread if cleanup is 
> needed for concurrent GCs.
>
> Moved inner metaspace cleaning back to class unloading, unless using 
> concurrent GC.  There we initiate a safepoint if inner metaspaces 
> require cleaning.
>
> Tested with tier1-6.
>
> open webrev at http://cr.openjdk.java.net/~coleenp/2020/8252043.01/webrev
> bug link https://bugs.openjdk.java.net/browse/JDK-8252043
>
> Thanks,
> Coleen