RFR: Disable merged cleanup for full GC

[Aleksey Shipilev]

On 06/29/2017 07:55 AM, Aleksey Shipilev wrote:
> On 06/28/2017 10:41 PM, Roman Kennke wrote:
>> The 'solution' for now is to disable merged monitor deflation
>> for full GC:
>>
>> http://cr.openjdk.java.net/~rkennke/disable-merged-cleanup-fullgc/webrev.00/
> 
> Okay, good!

I now wonder if this is a harbinger of larger problem: what if Full GC hits when
there are forwarded objects, and there are references to both copies in heap?
Would it keep both copies alive?

I guess we need to first complete the marking phase in Full GC, which would need
to update references (need_update_refs = true is set unconditionally, but it is
useless with disabled read barriers?), then turn read barriers on, and go on
with moving the objects.

Thanks,
-Aleksey