[8] RFR: Shenandoah: JNI weak roots are always cleared before Full GC mark

[Kornel Pal]

Hi Zhengyu,

Thank you for getting back to me and preparing the change this quickly.

I'm looking forward to see the change in the nightly builds.

Thank you,
Kornel

On 2020-08-28. 14:36, Zhengyu Gu wrote:
> Hi Kornel,
> 
> Yes, I will RFR to backout this workaround.
> 
> Thanks,
> 
> -Zhengyu
> 
> On 8/28/20 12:52 AM, Kornel Pal wrote:
>> Hi Aleksey,
>>
>> Thank you very much for all the dedicated work on Shenandoah GC, it 
>> really is useful.
>>
>> I wonder whether this workaround could safely be removed, now that 
>> JDK-8248041 was backported to 8u.
>>
>> Thank you,
>> Kornel
>>
>> On 2020-06-22 19:39, Aleksey Shipilev wrote:
>>> Amir found the crash with Cassandra that started to happen recently 
>>> with Shenandoah 8u. It
>>> reproduces more or less reliably with starting Cassandra 3.11.4 with 
>>> fastdebug build and
>>> -XX:ShenandoahGCMode=passive -XX:-ShenandoahDegeneratedGC.
>>>
>>> This is a symptom of a larger problem (see JDK-8248041), but 8u it is 
>>> catastrophic due to clearing
>>> of the weak roots.
>>>
>>> Fix:
>>> https://cr.openjdk.java.net/~shade/shenandoah/8u-fullgc-jni-weak/webrev.01/ 
>>>
>>>
>>> Testing: hotspot_gc_shenandoah; Cassandra tests
>>>
>>
>