RFR(XS): 8248799: Shenandoah: Claim threads token in constructor of ShenandoahRootVerifier

[Zhengyu Gu]

Looks good.

-Zhengyu

Sent from my iPad

> On Jul 3, 2020, at 8:35 AM, rkennke at redhat.com wrote:
> 
> In JDK-8248725 I changed thread iteration in ShenandoahRootVerifier
> from serial to parallel, but we also need to change the thread-claim-
> token in order for it to work. 
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8248799
> Testing: hotspot_gc_shenandoah
> 
> Fix:
> 
> diff -r 505a6165d85a -r 8c64644e2619
> src/hotspot/share/gc/shenandoah/shenandoahRootVerifier.cpp
> ---
> a/src/hotspot/share/gc/shenandoah/shenandoahRootVerifier.cpp        Fr
> i Jul 03 11:09:59 2020 +0200
> +++
> b/src/hotspot/share/gc/shenandoah/shenandoahRootVerifier.cpp        Fri
> Jul 03 14:31:11 2020 +0200
> @@ -46,6 +46,7 @@
> STATIC_ASSERT((static_cast<uint>(ShenandoahRootVerifier::AllRoots) +
> 1) > static_cast<uint>(ShenandoahRootVerifier::AllRoots));
> 
> ShenandoahRootVerifier::ShenandoahRootVerifier(RootTypes types) :
> _types(types) {
> +  Threads::change_thread_claim_token();
> }
> 
> void ShenandoahRootVerifier::excludes(RootTypes types) {
>