--- a/src/share/vm/gc_interface/collectedHeap.hpp	Thu Sep 16 13:45:55 2010 -0700
+++ b/src/share/vm/gc_interface/collectedHeap.hpp	Mon Sep 20 14:38:38 2010 -0700
@@ -59,6 +59,8 @@
   MemRegion _reserved;
   BarrierSet* _barrier_set;
   bool _is_gc_active;
+  int _n_par_threads;
+
   unsigned int _total_collections;          // ... started
   unsigned int _total_full_collections;     // ... started
   NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
@@ -293,6 +295,12 @@
   }
   GCCause::Cause gc_cause() { return _gc_cause; }
 
+  // Number of threads currently working on GC tasks.
+  int n_par_threads() { return _n_par_threads; }
+
+  // May be overridden to set additional parallelism.
+  virtual void set_par_threads(int t) { _n_par_threads = t; };
+
   // Preload classes into the shared portion of the heap, and then dump
   // that data to a file so that it can be loaded directly by another
   // VM (then terminate).
@@ -606,6 +614,14 @@
     return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
   }
 #endif
+
+ public:
+  // This is a convenience method that is used in cases where
+  // the actual number of GC worker threads is not pertinent but
+  // only whether there more than 0.  Use of this method helps
+  // reduce the occurrence of ParallelGCThreads to uses where the
+  // actual number may be germane.
+  static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; }
 };
 
 // Class to set and reset the GC cause for a CollectedHeap.