--- old/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp	2020-05-27 08:58:06.313540495 -0400
+++ new/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp	2020-05-27 08:58:06.179539819 -0400
@@ -174,7 +174,10 @@
       rp = NULL;
     }
 
-    _cm->concurrent_scan_code_roots(worker_id, rp);
+    if (!heap->unload_classes()) {
+      _cm->concurrent_scan_code_roots(worker_id, rp);
+    }
+
     _cm->mark_loop(worker_id, _terminator, rp,
                    true, // cancellable
                    ShenandoahStringDedup::is_enabled()); // perform string dedup
@@ -267,7 +270,8 @@
       }
     }
 
-    if (heap->is_degenerated_gc_in_progress()) {
+    if (heap->is_degenerated_gc_in_progress() &&
+        !heap->unload_classes()) {
       // Degenerated cycle may bypass concurrent cycle, so code roots might not be scanned,
       // let's check here.
       _cm->concurrent_scan_code_roots(worker_id, rp);