--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Tue Apr 12 14:46:02 2016 -0400
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Wed Apr 13 17:00:54 2016 -0400
@@ -2742,7 +2742,7 @@
   _cmThread->print_on(st);
   st->cr();
   _cm->print_worker_threads_on(st);
-  _cg1r->print_worker_threads_on(st);
+  _cg1r->print_worker_threads_on(st); // also prints the sample thread
   if (G1StringDedup::is_enabled()) {
     G1StringDedup::print_worker_threads_on(st);
   }
@@ -2751,7 +2751,8 @@
 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
   workers()->threads_do(tc);
   tc->do_thread(_cmThread);
-  _cg1r->threads_do(tc);
+  _cm->threads_do(tc);
+  _cg1r->threads_do(tc); // also iterates over the sample thread
   if (G1StringDedup::is_enabled()) {
     G1StringDedup::threads_do(tc);
   }