[11u] RFR (S) 8245880: Shenandoah: check class unloading flag early in concurrent code root scan

[Roman Kennke]

Looks good to me! Thanks!

Roman

On Tue, 2020-08-18 at 12:22 +0200, Aleksey Shipilev wrote:
> Original bug:
>    https://bugs.openjdk.java.net/browse/JDK-8245880
>    https://hg.openjdk.java.net/jdk/jdk/rev/3a8634555a01
> 
> The patch does apply cleanly to 11u, because the usual MutexLockerEx
> -> MutexLocker change. 
> Reapplied the hunk by hand.
> 
> 11u webrev:
>    https://cr.openjdk.java.net/~shade/8245880/webrev.11u.01/
> 
> Testing: hotspot_gc_shenandoah {fastdebug,release}, tier{1,2} with
> Shenandoah
>