--- a/hotspot/src/share/vm/oops/instanceKlass.cpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/oops/instanceKlass.cpp	Tue Jan 08 14:04:25 2013 -0500
@@ -160,6 +160,8 @@
 
 #endif //  ndef DTRACE_ENABLED
 
+volatile int InstanceKlass::_total_instanceKlass_count = 0;
+
 Klass* InstanceKlass::allocate_instance_klass(ClassLoaderData* loader_data,
                                                 int vtable_len,
                                                 int itable_len,
@@ -203,6 +205,7 @@
         access_flags, !host_klass.is_null());
   }
 
+  Atomic::inc(&_total_instanceKlass_count);
   return ik;
 }
 
@@ -2306,6 +2309,9 @@
   if (_array_name != NULL)  _array_name->decrement_refcount();
   if (_source_file_name != NULL) _source_file_name->decrement_refcount();
   if (_source_debug_extension != NULL) FREE_C_HEAP_ARRAY(char, _source_debug_extension, mtClass);
+
+  assert(_total_instanceKlass_count >= 1, "Sanity check");
+  Atomic::dec(&_total_instanceKlass_count);
 }
 
 void InstanceKlass::set_source_file_name(Symbol* n) {

--- a/hotspot/src/share/vm/oops/instanceKlass.hpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/oops/instanceKlass.hpp	Tue Jan 08 14:04:25 2013 -0500
@@ -31,6 +31,7 @@
 #include "oops/fieldInfo.hpp"
 #include "oops/instanceOop.hpp"
 #include "oops/klassVtable.hpp"
+#include "runtime/atomic.hpp"
 #include "runtime/handles.hpp"
 #include "runtime/os.hpp"
 #include "utilities/accessFlags.hpp"
@@ -170,6 +171,11 @@
     initialization_error                // error happened during initialization
   };
 
+  static int number_of_instance_classes() { return _total_instanceKlass_count; }
+
+ private:
+  static volatile int _total_instanceKlass_count;
+
  protected:
   // Protection domain.
   oop             _protection_domain;

--- a/hotspot/src/share/vm/services/memBaseline.cpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/services/memBaseline.cpp	Tue Jan 08 14:04:25 2013 -0500
@@ -22,7 +22,6 @@
  *
  */
 #include "precompiled.hpp"
-#include "classfile/systemDictionary.hpp"
 #include "memory/allocation.hpp"
 #include "services/memBaseline.hpp"
 #include "services/memTracker.hpp"
@@ -349,7 +348,7 @@
   reset();
   _baselined = baseline_malloc_summary(snapshot._alloc_ptrs) &&
                baseline_vm_summary(snapshot._vm_ptrs);
-  _number_of_classes = SystemDictionary::number_of_classes();
+  _number_of_classes = snapshot.number_of_classes();
 
   if (!summary_only && MemTracker::track_callsite() && _baselined) {
     _baselined =  baseline_malloc_details(snapshot._alloc_ptrs) &&

--- a/hotspot/src/share/vm/services/memRecorder.cpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/services/memRecorder.cpp	Tue Jan 08 14:04:25 2013 -0500
@@ -84,10 +84,13 @@
     }
     delete _pointer_records;
   }
-  if (_next != NULL) {
-    delete _next;
+  // delete all linked recorders
+  while (_next != NULL) {
+    MemRecorder* tmp = _next;
+    _next = _next->next();
+    tmp->set_next(NULL);
+    delete tmp;
   }
-
   Atomic::dec(&_instance_count);
 }
 

--- a/hotspot/src/share/vm/services/memRecorder.hpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/services/memRecorder.hpp	Tue Jan 08 14:04:25 2013 -0500
@@ -203,6 +203,7 @@
   friend class MemSnapshot;
   friend class MemTracker;
   friend class MemTrackWorker;
+  friend class GenerationData;
 
  protected:
   // the array that holds memory records

--- a/hotspot/src/share/vm/services/memSnapshot.cpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/services/memSnapshot.cpp	Tue Jan 08 14:04:25 2013 -0500
@@ -384,6 +384,7 @@
   _staging_area.init();
   _lock = new (std::nothrow) Mutex(Monitor::max_nonleaf - 1, "memSnapshotLock");
   NOT_PRODUCT(_untracked_count = 0;)
+  _number_of_classes = 0;
 }
 
 MemSnapshot::~MemSnapshot() {
@@ -479,7 +480,7 @@
 
 
 // promote data to next generation
-bool MemSnapshot::promote() {
+bool MemSnapshot::promote(int number_of_classes) {
   assert(_alloc_ptrs != NULL && _vm_ptrs != NULL, "Just check");
   assert(_staging_area.malloc_data() != NULL && _staging_area.vm_data() != NULL,
          "Just check");
@@ -496,6 +497,7 @@
 
   NOT_PRODUCT(check_malloc_pointers();)
   _staging_area.clear();
+  _number_of_classes = number_of_classes;
   return promoted;
 }
 

--- a/hotspot/src/share/vm/services/memSnapshot.hpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/services/memSnapshot.hpp	Tue Jan 08 14:04:25 2013 -0500
@@ -355,6 +355,9 @@
   // the lock to protect this snapshot
   Monitor*              _lock;
 
+  // the number of instance classes
+  int                   _number_of_classes;
+
   NOT_PRODUCT(size_t    _untracked_count;)
   friend class MemBaseline;
 
@@ -375,8 +378,9 @@
   // merge a per-thread memory recorder into staging area
   bool merge(MemRecorder* rec);
   // promote staged data to snapshot
-  bool promote();
+  bool promote(int number_of_classes);
 
+  int  number_of_classes() const { return _number_of_classes; }
 
   void wait(long timeout) {
     assert(_lock != NULL, "Just check");

--- a/hotspot/src/share/vm/services/memTrackWorker.cpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/services/memTrackWorker.cpp	Tue Jan 08 14:04:25 2013 -0500
@@ -29,6 +29,16 @@
 #include "utilities/decoder.hpp"
 #include "utilities/vmError.hpp"
 
+
+void GenerationData::reset() {
+  _number_of_classes = 0;
+  while (_recorder_list != NULL) {
+    MemRecorder* tmp = _recorder_list;
+    _recorder_list = _recorder_list->next();
+    MemTracker::release_thread_recorder(tmp);
+  }
+}
+
 MemTrackWorker::MemTrackWorker() {
   // create thread uses cgc thread type for now. We should revisit
   // the option, or create new thread type.
@@ -39,7 +49,7 @@
   if (!has_error()) {
     _head = _tail = 0;
     for(int index = 0; index < MAX_GENERATIONS; index ++) {
-      _gen[index] = NULL;
+      ::new ((void*)&_gen[index]) GenerationData();
     }
   }
   NOT_PRODUCT(_sync_point_count = 0;)
@@ -49,10 +59,7 @@
 
 MemTrackWorker::~MemTrackWorker() {
   for (int index = 0; index < MAX_GENERATIONS; index ++) {
-    MemRecorder* rc = _gen[index];
-    if (rc != NULL) {
-      delete rc;
-    }
+    _gen[index].reset();
   }
 }
 
@@ -90,12 +97,7 @@
     {
       // take a recorder from earliest generation in buffer
       ThreadCritical tc;
-      rec = _gen[_head];
-      if (rec != NULL) {
-        _gen[_head] = rec->next();
-      }
-      assert(count_recorder(_gen[_head]) <= MemRecorder::_instance_count,
-        "infinite loop after dequeue");
+      rec = _gen[_head].next_recorder();
     }
     if (rec != NULL) {
       // merge the recorder into staging area
@@ -109,16 +111,20 @@
       // no more recorder to merge, promote staging area
       // to snapshot
       if (_head != _tail) {
+        long number_of_classes;
         {
           ThreadCritical tc;
-          if (_gen[_head] != NULL || _head == _tail) {
+          if (_gen[_head].has_more_recorder() || _head == _tail) {
             continue;
           }
+          number_of_classes = _gen[_head].number_of_classes();
+          _gen[_head].reset();
+
           // done with this generation, increment _head pointer
           _head = (_head + 1) % MAX_GENERATIONS;
         }
         // promote this generation data to snapshot
-        if (!snapshot->promote()) {
+        if (!snapshot->promote(number_of_classes)) {
           // failed to promote, means out of memory
           MemTracker::shutdown(MemTracker::NMT_out_of_memory);
         }
@@ -126,8 +132,8 @@
         snapshot->wait(1000);
         ThreadCritical tc;
         // check if more data arrived
-        if (_gen[_head] == NULL) {
-          _gen[_head] = MemTracker::get_pending_recorders();
+        if (!_gen[_head].has_more_recorder()) {
+          _gen[_head].add_recorders(MemTracker::get_pending_recorders());
         }
       }
     }
@@ -147,7 +153,7 @@
 //   1. add all recorders in pending queue to current generation
 //   2. increase generation
 
-void MemTrackWorker::at_sync_point(MemRecorder* rec) {
+void MemTrackWorker::at_sync_point(MemRecorder* rec, int number_of_classes) {
   NOT_PRODUCT(_sync_point_count ++;)
   assert(count_recorder(rec) <= MemRecorder::_instance_count,
     "pending queue has infinite loop");
@@ -155,23 +161,15 @@
   bool out_of_generation_buffer = false;
   // check shutdown state inside ThreadCritical
   if (MemTracker::shutdown_in_progress()) return;
+
+  _gen[_tail].set_number_of_classes(number_of_classes);
   // append the recorders to the end of the generation
-  if( rec != NULL) {
-    MemRecorder* cur_head = _gen[_tail];
-    if (cur_head == NULL) {
-      _gen[_tail] = rec;
-    } else {
-      while (cur_head->next() != NULL) {
-        cur_head = cur_head->next();
-      }
-      cur_head->set_next(rec);
-    }
-  }
-  assert(count_recorder(rec) <= MemRecorder::_instance_count,
+  _gen[_tail].add_recorders(rec);
+  assert(count_recorder(_gen[_tail].peek()) <= MemRecorder::_instance_count,
     "after add to current generation has infinite loop");
   // we have collected all recorders for this generation. If there is data,
   // we need to increment _tail to start a new generation.
-  if (_gen[_tail] != NULL || _head == _tail) {
+  if (_gen[_tail].has_more_recorder()  || _head == _tail) {
     _tail = (_tail + 1) % MAX_GENERATIONS;
     out_of_generation_buffer = (_tail == _head);
   }
@@ -194,7 +192,7 @@
 int MemTrackWorker::count_pending_recorders() const {
   int count = 0;
   for (int index = 0; index < MAX_GENERATIONS; index ++) {
-    MemRecorder* head = _gen[index];
+    MemRecorder* head = _gen[index].peek();
     if (head != NULL) {
       count += count_recorder(head);
     }

--- a/hotspot/src/share/vm/services/memTrackWorker.hpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/services/memTrackWorker.hpp	Tue Jan 08 14:04:25 2013 -0500
@@ -32,17 +32,58 @@
 // Maximum MAX_GENERATIONS generation data can be tracked.
 #define MAX_GENERATIONS  512
 
+class GenerationData : public _ValueObj {
+ private:
+  int           _number_of_classes;
+  MemRecorder*  _recorder_list;
+
+ public:
+  GenerationData(): _number_of_classes(0), _recorder_list(NULL) { }
+
+  inline int  number_of_classes() const { return _number_of_classes; }
+  inline void set_number_of_classes(long num) { _number_of_classes = num; }
+
+  inline MemRecorder* next_recorder() {
+    if (_recorder_list == NULL) {
+      return NULL;
+    } else {
+      MemRecorder* tmp = _recorder_list;
+      _recorder_list = _recorder_list->next();
+      return tmp;
+    }
+  }
+
+  inline bool has_more_recorder() const {
+    return (_recorder_list != NULL);
+  }
+
+  // add recorders to this generation
+  void add_recorders(MemRecorder* head) {
+    if (head != NULL) {
+      if (_recorder_list == NULL) {
+        _recorder_list = head;
+      } else {
+        MemRecorder* tmp = _recorder_list;
+        for (; tmp->next() != NULL; tmp = tmp->next());
+        tmp->set_next(head);
+      }
+    }
+  }
+
+  void reset();
+
+  NOT_PRODUCT(MemRecorder* peek() const { return _recorder_list; })
+};
 
 class MemTrackWorker : public NamedThread {
  private:
-  // circular buffer. This buffer contains recorders to be merged into global
+  // circular buffer. This buffer contains generation data to be merged into global
   // snaphsot.
-  // Each slot holds a linked list of memory recorders, that contains one
-  // generation of memory data.
-  MemRecorder*  _gen[MAX_GENERATIONS];
-  int           _head, _tail; // head and tail pointers to above circular buffer
+  // Each slot holds a generation
+  GenerationData  _gen[MAX_GENERATIONS];
+  int             _head, _tail; // head and tail pointers to above circular buffer
 
-  bool          _has_error;
+  bool            _has_error;
 
  public:
   MemTrackWorker();
@@ -56,7 +97,7 @@
   inline bool has_error() const { return _has_error; }
 
   // task at synchronization point
-  void at_sync_point(MemRecorder* pending_recorders);
+  void at_sync_point(MemRecorder* pending_recorders, int number_of_classes);
 
   // for debugging purpose, they are not thread safe.
   NOT_PRODUCT(static int count_recorder(const MemRecorder* head);)

--- a/hotspot/src/share/vm/services/memTracker.cpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/services/memTracker.cpp	Tue Jan 08 14:04:25 2013 -0500
@@ -23,6 +23,7 @@
  */
 #include "precompiled.hpp"
 
+#include "oops/instanceKlass.hpp"
 #include "runtime/atomic.hpp"
 #include "runtime/interfaceSupport.hpp"
 #include "runtime/mutexLocker.hpp"
@@ -485,7 +486,7 @@
       }
       // check _worker_thread with lock to avoid racing condition
       if (_worker_thread != NULL) {
-        _worker_thread->at_sync_point(pending_recorders);
+        _worker_thread->at_sync_point(pending_recorders, InstanceKlass::number_of_instance_classes());
       }
 
       assert(SequenceGenerator::peek() == 1, "Should not have memory activities during sync-point");

--- a/hotspot/src/share/vm/services/memTracker.hpp	Fri Dec 07 10:55:16 2012 -0800
+++ b/hotspot/src/share/vm/services/memTracker.hpp	Tue Jan 08 14:04:25 2013 -0500
@@ -142,6 +142,7 @@
  * MemTracker is the 'gate' class to native memory tracking runtime.
  */
 class MemTracker : AllStatic {
+  friend class GenerationData;
   friend class MemTrackWorker;
   friend class MemSnapshot;
   friend class SyncThreadRecorderClosure;