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

[Kornel Pal]

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
>