RFR: Rework ClassUnloading* flags handling

[Roman Kennke]

Am 18.05.2018 um 16:41 schrieb Aleksey Shipilev:
> On 05/18/2018 04:40 PM, Roman Kennke wrote:
>> Am 18.05.2018 um 16:26 schrieb Aleksey Shipilev:
>>> http://cr.openjdk.java.net/~shade/shenandoah/class-unload-rework/webrev.01/
>>>
>>> We have lost some of this during upstream merges, and we have not noticed because no tests verified
>>> how we handle ClassUnloading* flags. This patch makes sure ClassUnloading* flags are treated well by
>>> Shenandoah in every mode. New tests capture the intended behavior, including OOME when class
>>> unloading is disabled and classes leak.
>>>
>>> Testing: hotspot_gc_shenandoah
>>>
>>> Thanks,
>>> -Aleksey
>>>
>>
>> One question: it does not disable concurrent class unloading by default,
>> right? I'm asking because if I understood correctly, you meant to do that?
> 
> Yes, separately, because it has performance implications that I still study. After this
> infrastructure fix, making class unloading opt-in is a two-liner fix.

Ok.

Roman