--- old/src/hotspot/share/gc/shenandoah/shenandoahMarkCompact.cpp	2020-06-18 12:30:33.117844476 +0200
+++ new/src/hotspot/share/gc/shenandoah/shenandoahMarkCompact.cpp	2020-06-18 12:30:32.629831029 +0200
@@ -140,7 +140,10 @@
     _preserved_marks->init(heap->workers()->active_workers());
   }
 
-  heap->make_parsable(true);
+  if (UseTLAB) {
+    heap->gclabs_retire(true);
+    heap->tlabs_retire(true);
+  }
 
   OrderAccess::fence();