--- old/src/hotspot/share/gc/shared/collectedHeap.hpp	2020-04-27 10:20:16.783853546 +0200
+++ new/src/hotspot/share/gc/shared/collectedHeap.hpp	2020-04-27 10:20:16.591850421 +0200
@@ -29,6 +29,7 @@
 #include "gc/shared/gcWhen.hpp"
 #include "gc/shared/verifyOption.hpp"
 #include "memory/allocation.hpp"
+#include "memory/heapInspection.hpp"
 #include "runtime/handles.hpp"
 #include "runtime/perfData.hpp"
 #include "runtime/safepoint.hpp"
@@ -43,6 +44,7 @@
 // class defines the functions that a heap must implement, and contains
 // infrastructure common to all heaps.
 
+class AbstractGangTask;
 class AdaptiveSizePolicy;
 class BarrierSet;
 class GCHeapSummary;
@@ -84,6 +86,11 @@
   }
 };
 
+class ParallelObjectIterator : public CHeapObj<mtGC> {
+public:
+  virtual void object_iterate(ObjectClosure* cl, uint worker_id) = 0;
+};
+
 //
 // CollectedHeap
 //   GenCollectedHeap
@@ -386,6 +393,13 @@
   // Iterate over all objects, calling "cl.do_object" on each.
   virtual void object_iterate(ObjectClosure* cl) = 0;
 
+  virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num) {
+    return NULL;
+  }
+
+  // Run given task. Possibly in parallel if the GC supports it.
+  virtual void run_task(AbstractGangTask* task) = 0;
+
   // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
   virtual void keep_alive(oop obj) {}