--- old/src/share/vm/memory/genCollectedHeap.cpp	2015-04-02 12:39:15.780305898 +0200
+++ new/src/share/vm/memory/genCollectedHeap.cpp	2015-04-02 12:39:15.672305902 +0200
@@ -91,6 +91,7 @@
                             /* are_ConcurrentGC_threads */false);
     _workers->initialize_workers();
   } else {
+    // Serial GC does not use workers
     _workers = NULL;
   }
 }