hg: jdk/sandbox: 8241142: Shenandoah: should not use parallel reference processing with single GC thread

[chris.hegarty at oracle.com]

Changeset: 5393acb9f896
Author:    shade
Date:      2020-04-14 21:17 +0200
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/5393acb9f896

8241142: Shenandoah: should not use parallel reference processing with single GC thread
Reviewed-by: shade
Contributed-by: Aditya Mandaleeka <adityam at microsoft.com>

! src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp