--- old/src/share/vm/gc/shared/referenceProcessor.hpp	2016-03-16 08:24:45.390807461 -0700
+++ new/src/share/vm/gc/shared/referenceProcessor.hpp	2016-03-16 08:24:45.290807456 -0700
@@ -225,7 +225,7 @@
 
   uint num_q()                             { return _num_q; }
   uint max_num_q()                         { return _max_num_q; }
-  void set_active_mt_degree(uint v)        { _num_q = v; }
+  void set_active_mt_degree(uint v);
 
   DiscoveredList* discovered_refs()        { return _discovered_refs; }
 
@@ -327,7 +327,7 @@
   uint next_id() {
     uint id = _next_id;
     assert(!_discovery_is_mt, "Round robin should only be used in serial discovery");
-    if (++_next_id >= _num_q) {
+    if (++_next_id == _num_q) {
       _next_id = 0;
     }
     assert(_next_id < _num_q, "_next_id %u _num_q %u _max_num_q %u", _next_id, _num_q, _max_num_q);