--- old/src/hotspot/share/gc/g1/g1CollectedHeap.hpp	2020-04-25 22:41:12.249526187 +0800
+++ new/src/hotspot/share/gc/g1/g1CollectedHeap.hpp	2020-04-25 22:41:12.085526918 +0800
@@ -550,7 +550,7 @@
 
   // Runs the given AbstractGangTask with the current active workers, returning the
   // total time taken.
-  Tickspan run_task(AbstractGangTask* task);
+  virtual Tickspan run_task(AbstractGangTask* task);
 
   G1Allocator* allocator() {
     return _allocator;