--- old/src/hotspot/share/gc/g1/g1CollectedHeap.hpp	2020-07-15 16:23:41.459745940 +0800
+++ new/src/hotspot/share/gc/g1/g1CollectedHeap.hpp	2020-07-15 16:23:41.199745931 +0800
@@ -549,9 +549,12 @@
 
   WorkGang* workers() const { return _workers; }
 
-  // Runs the given AbstractGangTask with the current active workers, returning the
-  // total time taken.
-  Tickspan run_task(AbstractGangTask* task);
+  // Runs the given AbstractGangTask with the current active workers.
+  virtual void run_task(AbstractGangTask* task);
+
+  // Runs the given AbstractGangTask with the current active workers,
+  // returning the total time taken.
+  Tickspan run_task_timed(AbstractGangTask* task);
 
   G1Allocator* allocator() {
     return _allocator;
@@ -1168,9 +1171,13 @@
 
   // Iteration functions.
 
+  void object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer);
+
   // Iterate over all objects, calling "cl.do_object" on each.
   virtual void object_iterate(ObjectClosure* cl);
 
+  virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num);
+
   // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
   virtual void keep_alive(oop obj);