--- old/src/share/vm/memory/genCollectedHeap.cpp	2015-04-02 12:38:41.408307333 +0200
+++ new/src/share/vm/memory/genCollectedHeap.cpp	2015-04-02 12:38:41.292307338 +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() {