--- a/src/share/vm/memory/gcLocker.hpp	Wed Jun 10 14:57:21 2009 -0700
+++ b/src/share/vm/memory/gcLocker.hpp	Thu Jun 11 12:40:00 2009 -0700
@@ -242,6 +242,31 @@
 #endif
 };
 
+// A SkipGCALot object is used to elide the usual effect of gc-a-lot
+// over a section of execution by a thread. Currently, it's used only to
+// prevent re-entrant calls to GC.
+class SkipGCALot : public StackObj {
+  private:
+   bool _saved;
+   Thread* _t;
+
+  public:
+#ifdef ASSERT
+    SkipGCALot(Thread* t) : _t(t) {
+      _saved = _t->skip_gcalot();
+      _t->set_skip_gcalot(true);
+    }
+
+    ~SkipGCALot() {
+      assert(_t->skip_gcalot(), "Save-restore protocol invariant");
+      _t->set_skip_gcalot(_saved);
+    }
+#else
+    SkipGCALot(Thread* t) { }
+    ~SkipGCALot() { }
+#endif
+};
+
 // JRT_LEAF currently can be called from either _thread_in_Java or
 // _thread_in_native mode. In _thread_in_native, it is ok
 // for another thread to trigger GC. The rest of the JRT_LEAF