diff -r dcbb71b9e7c0 -r de99beff5c0e src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.cpp
--- a/src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.cpp	Fri Dec 14 16:52:17 2018 -0800
+++ b/src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.cpp	Mon Dec 17 11:37:40 2018 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -40,7 +40,8 @@
              "G1YoungRemSetSamplingThread monitor",
              true,
              Monitor::_safepoint_check_never),
-    _last_periodic_gc_attempt_s(os::elapsedTime()) {
+    _last_periodic_gc_attempt_s(os::elapsedTime()),
+    _vtime_accum(0) {
   set_name("G1 Young RemSet Sampling");
   create_and_start();
 }