--- old/src/hotspot/share/gc/shared/collectedHeap.cpp	2020-04-25 22:41:15.129513361 +0800
+++ new/src/hotspot/share/gc/shared/collectedHeap.cpp	2020-04-25 22:41:14.965514092 +0800
@@ -483,15 +483,6 @@
   }
 }
 
-Tickspan CollectedHeap::run_task(AbstractGangTask* task) {
-  Ticks start = Ticks::now();
-
-  // FIXME
-  Unimplemented();
-
-  return Ticks::now() - start;
-}
-
 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
   assert(timer != NULL, "timer is null");
   if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {