RFR (S) 8251336: Shenandoah: assert "only get here when SATB active" after JDK-8244997

[Kim Barrett]

> On Aug 11, 2020, at 5:02 PM, Coleen Phillimore <coleen.phillimore at oracle.com> wrote:
> 
> 
> 
> On 8/11/20 4:45 PM, Coleen Phillimore wrote:
>> 
>> 
>> On 8/11/20 1:48 PM, Kim Barrett wrote:
>>>> On Aug 11, 2020, at 10:41 AM, Coleen Phillimore <coleen.phillimore at oracle.com> wrote:
>>>> 
>>>> 
>>>> Kim's suggestion for this change looks really good.  I'm re-testing this now:
>>>> 
>>>> open webrev at http://cr.openjdk.java.net/~coleenp/2020/8251336.02/webrev
>>>> bug link https://bugs.openjdk.java.net/browse/JDK-8251336
>>> In release_oop_handles, because Service_lock is a "special" lock and
>>> touched in lots of places, I'd prefer the deletion not happen under
>>> the lock.  (I realize this uglifies the code a little bit.)
>> 
>> Because there was no performance reason to use lock free code for this, I add to and clean out the linked list under the Service_lock.  I chose a simple implementation because there was no performance or correctness issue to do otherwise.
>> 
>> I'd rather not change this to be ugly unless it's proven to not be correct or performant.
> 
> Scratch that.  I see what you mean. Like:
> 
> http://cr.openjdk.java.net/~coleenp/2020/8251336.03.incr/webrev/index.html
> 
> (sorry I had some other questions about making this lock free).
> 
> I'm re-testing this version now.

Yes, exactly.  That version looks good.