--- old/src/hotspot/share/gc/epsilon/epsilonHeap.cpp	2020-04-25 20:53:27.567352441 +0800
+++ new/src/hotspot/share/gc/epsilon/epsilonHeap.cpp	2020-04-25 20:53:27.399352953 +0800
@@ -296,6 +296,13 @@
   _space->object_iterate(cl);
 }
 
+// No workGang for EpsilonHeap, work serially with thread 0
+Tickspan EpsilonHeap::run_task(AbstractGangTask* task) {
+  Ticks start = Ticks::now();
+  task->work(0);
+  return Ticks::now() - start;
+}
+
 void EpsilonHeap::print_on(outputStream *st) const {
   st->print_cr("Epsilon Heap");