--- old/src/hotspot/share/gc/epsilon/epsilonHeap.hpp	2020-08-05 21:29:25.033604268 +0800
+++ new/src/hotspot/share/gc/epsilon/epsilonHeap.hpp	2020-08-05 21:29:24.741604257 +0800
@@ -119,6 +119,10 @@
   // No GC threads
   virtual void gc_threads_do(ThreadClosure* tc) const {}
 
+  // Runs the given AbstractGangTask with the current active workers
+  // No workGang for EpsilonHeap, work serially with thread 0
+  virtual void run_task(AbstractGangTask* task) { task->work(0); }
+
   // No nmethod handling
   virtual void register_nmethod(nmethod* nm) {}
   virtual void unregister_nmethod(nmethod* nm) {}
@@ -141,8 +145,6 @@
   virtual void print_tracing_info() const;
   virtual bool print_location(outputStream* st, void* addr) const;
 
-  // Runs the given AbstractGangTask with the current active workers.
-  virtual void run_task(AbstractGangTask* task);
 
 private:
   void print_heap_info(size_t used) const;