--- old/src/hotspot/share/gc/serial/serialHeap.cpp	2020-07-09 14:49:52.364515995 +0800
+++ new/src/hotspot/share/gc/serial/serialHeap.cpp	2020-07-09 14:49:52.208516487 +0800
@@ -87,3 +87,8 @@
   memory_pools.append(_old_pool);
   return memory_pools;
 }
+
+// No workGang for SerialHeap, work serially with thread 0.
+void SerialHeap::run_task(AbstractGangTask* task) {
+  task->work(0);
+}