--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/parMarkBitMap.hpp	Wed Apr 10 13:27:35 2013 +0200
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/parMarkBitMap.hpp	Wed Apr 10 14:26:49 2013 +0200
@@ -173,6 +173,12 @@
   void reset_counters();
 #endif  // #ifndef PRODUCT
 
+  void print_on_error(outputStream* st) const {
+    st->print_cr("Marking Bits: (ParMarkBitMap*) " PTR_FORMAT, this);
+    _beg_bits.print_on_error(st, " Begin Bits: ");
+    _end_bits.print_on_error(st, " End Bits:   ");
+  }
+
 #ifdef  ASSERT
   void verify_clear() const;
   inline void verify_bit(idx_t bit) const;