--- a/src/hotspot/share/gc/shared/workgroup.hpp	Tue Feb 20 16:18:25 2018 -0600
+++ b/src/hotspot/share/gc/shared/workgroup.hpp	Wed Feb 21 07:46:40 2018 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 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
@@ -59,14 +59,9 @@
   const uint _gc_id;
 
  public:
-  AbstractGangTask(const char* name) :
+  explicit AbstractGangTask(const char* name) :
     _name(name),
-    _gc_id(GCId::current_raw())
-  {}
-
-  AbstractGangTask(const char* name, const uint gc_id) :
-    _name(name),
-    _gc_id(gc_id)
+    _gc_id(GCId::current_or_undefined())
   {}
 
   // The abstract work method.