--- old/src/share/vm/gc/g1/dirtyCardQueue.cpp	2016-07-21 12:32:30.043639238 +0200
+++ new/src/share/vm/gc/g1/dirtyCardQueue.cpp	2016-07-21 12:32:29.955636589 +0200
@@ -122,7 +122,7 @@
 
 // Determines how many mutator threads can process the buffers in parallel.
 uint DirtyCardQueueSet::num_par_ids() {
-  return (uint)os::processor_count();
+  return (uint)os::initial_active_processor_count();
 }
 
 void DirtyCardQueueSet::initialize(CardTableEntryClosure* cl,