--- a/hotspot/src/share/vm/services/memTracker.cpp	Wed Jul 04 15:55:45 2012 -0400
+++ b/hotspot/src/share/vm/services/memTracker.cpp	Thu Jul 19 09:05:42 2012 -0400
@@ -351,21 +351,17 @@
     }
 
     if (thread != NULL) {
-#ifdef ASSERT
-      // cause assertion on stack base. This ensures that threads call
-      // Thread::record_stack_base_and_size() method, which will create
-      // thread native stack records.
-      thread->stack_base();
-#endif
-      // for a JavaThread, if it is running in native state, we need to transition it to
-      // VM state, so it can stop at safepoint. JavaThread running in VM state does not
-      // need lock to write records.
       if (thread->is_Java_thread() && ((JavaThread*)thread)->is_safepoint_visible()) {
-        if (((JavaThread*)thread)->thread_state() == _thread_in_native) {
-          ThreadInVMfromNative trans((JavaThread*)thread);
-          create_record_in_recorder(addr, flags, size, pc, thread);
+        JavaThread*      java_thread = static_cast<JavaThread*>(thread);
+        JavaThreadState  state = java_thread->thread_state();
+        if (SafepointSynchronize::safepoint_safe(java_thread, state)) {
+          // JavaThreads that are safepoint safe, can run through safepoint,
+          // so ThreadCritical is needed to ensure no threads at safepoint create
+          // new records while the records are being gathered and the sequence number is changing
+          ThreadCritical tc;
+          create_record_in_recorder(addr, flags, size, pc, java_thread);
         } else {
-          create_record_in_recorder(addr, flags, size, pc, thread);
+          create_record_in_recorder(addr, flags, size, pc, java_thread);
         }
       } else {
         // other threads, such as worker and watcher threads, etc. need to
@@ -390,10 +386,9 @@
 // write a record to proper recorder. No lock can be taken from this method
 // down.
 void MemTracker::create_record_in_recorder(address addr, MEMFLAGS flags,
-    size_t size, address pc, Thread* thread) {
-    assert(thread == NULL || thread->is_Java_thread(), "wrong thread");
+    size_t size, address pc, JavaThread* thread) {
 
-    MemRecorder* rc = get_thread_recorder((JavaThread*)thread);
+    MemRecorder* rc = get_thread_recorder(thread);
     if (rc != NULL) {
       rc->record(addr, flags, size, pc);
     }
@@ -460,17 +455,18 @@
       }
     }
     _sync_point_skip_count = 0;
-    // walk all JavaThreads to collect recorders
-    SyncThreadRecorderClosure stc;
-    Threads::threads_do(&stc);
-
-    _thread_count = stc.get_thread_count();
-    MemRecorder* pending_recorders = get_pending_recorders();
-
     {
       // This method is running at safepoint, with ThreadCritical lock,
       // it should guarantee that NMT is fully sync-ed.
       ThreadCritical tc;
+
+      // walk all JavaThreads to collect recorders
+      SyncThreadRecorderClosure stc;
+      Threads::threads_do(&stc);
+
+      _thread_count = stc.get_thread_count();
+      MemRecorder* pending_recorders = get_pending_recorders();
+
       if (_global_recorder != NULL) {
         _global_recorder->set_next(pending_recorders);
         pending_recorders = _global_recorder;
@@ -486,8 +482,6 @@
 
   // now, it is the time to shut whole things off
   if (_state == NMT_final_shutdown) {
-    _tracking_level = NMT_off;
-
     // walk all JavaThreads to delete all recorders
     SyncThreadRecorderClosure stc;
     Threads::threads_do(&stc);
@@ -499,8 +493,16 @@
         _global_recorder = NULL;
       }
     }
-
-    _state = NMT_shutdown;
+    MemRecorder* pending_recorders = get_pending_recorders();
+    if (pending_recorders != NULL) {
+      delete pending_recorders;
+    }
+    // try at a later sync point to ensure MemRecorder instance drops to zero to
+    // completely shutdown NMT
+    if (MemRecorder::_instance_count == 0) {
+      _state = NMT_shutdown;
+      _tracking_level = NMT_off;
+    }
   }
 }