diff -r c7cdaa576875 -r 5fe1c8494b49 hotspot/src/share/vm/memory/genCollectedHeap.cpp
--- a/hotspot/src/share/vm/memory/genCollectedHeap.cpp	Thu Apr 02 10:22:13 2015 +0200
+++ b/hotspot/src/share/vm/memory/genCollectedHeap.cpp	Thu Apr 02 16:06:07 2015 +0200
@@ -85,6 +85,15 @@
   _full_collections_completed(0)
 {
   assert(policy != NULL, "Sanity check");
+  if (UseConcMarkSweepGC) {
+    _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
+                            /* are_GC_task_threads */true,
+                            /* are_ConcurrentGC_threads */false);
+    _workers->initialize_workers();
+  } else {
+    // Serial GC does not use workers.
+    _workers = NULL;
+  }
 }
 
 jint GenCollectedHeap::initialize() {
@@ -166,7 +175,8 @@
 }
 
 void GenCollectedHeap::post_initialize() {
-  SharedHeap::post_initialize();
+  CollectedHeap::post_initialize();
+  ref_processing_init();
   GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
   guarantee(policy->is_generation_policy(), "Illegal policy type");
   assert((_young_gen->kind() == Generation::DefNew) ||
@@ -185,7 +195,6 @@
 }
 
 void GenCollectedHeap::ref_processing_init() {
-  SharedHeap::ref_processing_init();
   _young_gen->ref_processor_init();
   _old_gen->ref_processor_init();
 }
@@ -560,7 +569,8 @@
 }
 
 void GenCollectedHeap::set_par_threads(uint t) {
-  SharedHeap::set_par_threads(t);
+  assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
+  CollectedHeap::set_par_threads(t);
   set_n_termination(t);
 }
 
@@ -924,6 +934,11 @@
 }
 #endif
 
+void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
+  NoHeaderExtendedOopClosure no_header_cl(cl);
+  oop_iterate(&no_header_cl);
+}
+
 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
   _young_gen->oop_iterate(cl);
   _old_gen->oop_iterate(cl);
@@ -1093,11 +1108,6 @@
   }
 }
 
-void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
-  _young_gen->space_iterate(cl, true);
-  _old_gen->space_iterate(cl, true);
-}
-
 bool GenCollectedHeap::is_maximal_no_gc() const {
   return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
 }