--- a/hotspot/src/share/vm/gc_implementation/g1/dirtyCardQueue.hpp	Fri Oct 01 21:48:40 2010 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/dirtyCardQueue.hpp	Fri Oct 01 16:43:05 2010 -0400
@@ -37,11 +37,10 @@
 class DirtyCardQueue: public PtrQueue {
 public:
   DirtyCardQueue(PtrQueueSet* qset_, bool perm = false) :
-    PtrQueue(qset_, perm)
-  {
-    // Dirty card queues are always active.
-    _active = true;
-  }
+    // Dirty card queues are always active, so we create them with their
+    // active field set to true.
+    PtrQueue(qset_, perm, true /* active */) { }
+
   // Apply the closure to all elements, and reset the index to make the
   // buffer empty.  If a closure application returns "false", return
   // "false" immediately, halting the iteration.  If "consume" is true,

--- a/hotspot/src/share/vm/gc_implementation/g1/ptrQueue.hpp	Fri Oct 01 21:48:40 2010 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/ptrQueue.hpp	Fri Oct 01 16:43:05 2010 -0400
@@ -89,6 +89,10 @@
     return _buf == NULL ? 0 : _sz - _index;
   }
 
+  bool is_empty() {
+    return _buf == NULL || _sz == _index;
+  }
+
   // Set the "active" property of the queue to "b".  An enqueue to an
   // inactive thread is a no-op.  Setting a queue to inactive resets its
   // log to the empty state.

--- a/hotspot/src/share/vm/gc_implementation/g1/satbQueue.hpp	Fri Oct 01 21:48:40 2010 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/satbQueue.hpp	Fri Oct 01 16:43:05 2010 -0400
@@ -29,7 +29,12 @@
 class ObjPtrQueue: public PtrQueue {
 public:
   ObjPtrQueue(PtrQueueSet* qset_, bool perm = false) :
-    PtrQueue(qset_, perm, qset_->is_active()) { }
+    // SATB queues are only active during marking cycles. We create
+    // them with their active field set to false. If a thread is
+    // created during a cycle and its SATB queue needs to be activated
+    // before the thread starts running, we'll need to set its active
+    // field to true. This is done in JavaThread::initialize_queues().
+    PtrQueue(qset_, perm, false /* active */) { }
   // Apply the closure to all elements, and reset the index to make the
   // buffer empty.
   void apply_closure(ObjectClosure* cl);

--- a/hotspot/src/share/vm/gc_implementation/shared/concurrentGCThread.cpp	Fri Oct 01 21:48:40 2010 -0700
+++ b/hotspot/src/share/vm/gc_implementation/shared/concurrentGCThread.cpp	Fri Oct 01 16:43:05 2010 -0400
@@ -185,7 +185,7 @@
   instanceKlassHandle klass (THREAD, k);
   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
 
-  const char thread_name[] = "Surrogate Locker Thread (CMS)";
+  const char thread_name[] = "Surrogate Locker Thread (Concurrent GC)";
   Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL);
 
   // Initialize thread_oop to put it into the system threadGroup

--- a/hotspot/src/share/vm/runtime/thread.cpp	Fri Oct 01 21:48:40 2010 -0700
+++ b/hotspot/src/share/vm/runtime/thread.cpp	Fri Oct 01 16:43:05 2010 -0400
@@ -1644,7 +1644,29 @@
   satb_mark_queue().flush();
   dirty_card_queue().flush();
 }
-#endif
+
+void JavaThread::initialize_queues() {
+  assert(!SafepointSynchronize::is_at_safepoint(),
+         "we should not be at a safepoint");
+
+  ObjPtrQueue& satb_queue = satb_mark_queue();
+  SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
+  // The SATB queue should have been constructed with its active
+  // field set to false.
+  assert(!satb_queue.is_active(), "SATB queue should not be active");
+  assert(satb_queue.is_empty(), "SATB queue should be empty");
+  // If we are creating the thread during a marking cycle, we should
+  // set the active field of the SATB queue to true.
+  if (satb_queue_set.is_active()) {
+    satb_queue.set_active(true);
+  }
+
+  DirtyCardQueue& dirty_queue = dirty_card_queue();
+  // The dirty card queue should have been constructed with its
+  // active field set to true.
+  assert(dirty_queue.is_active(), "dirty card queue should be active");
+}
+#endif // !SERIALGC
 
 void JavaThread::cleanup_failed_attach_current_thread() {
   if (get_thread_profiler() != NULL) {
@@ -3626,6 +3648,10 @@
 void Threads::add(JavaThread* p, bool force_daemon) {
   // The threads lock must be owned at this point
   assert_locked_or_safepoint(Threads_lock);
+
+  // See the comment for this method in thread.hpp for its purpose and
+  // why it is called here.
+  p->initialize_queues();
   p->set_next(_thread_list);
   _thread_list = p;
   _number_of_threads++;

--- a/hotspot/src/share/vm/runtime/thread.hpp	Fri Oct 01 21:48:40 2010 -0700
+++ b/hotspot/src/share/vm/runtime/thread.hpp	Fri Oct 01 16:43:05 2010 -0400
@@ -1487,6 +1487,29 @@
   }
 #endif // !SERIALGC
 
+  // This method initializes the SATB and dirty card queues before a
+  // JavaThread is added to the Java thread list. Right now, we don't
+  // have to do anything to the dirty card queue (it should have been
+  // activated when the thread was created), but we have to activate
+  // the SATB queue if the thread is created while a marking cycle is
+  // in progress. The activation / de-activation of the SATB queues at
+  // the beginning / end of a marking cycle is done during safepoints
+  // so we have to make sure this method is called outside one to be
+  // able to safely read the active field of the SATB queue set. Right
+  // now, it is called just before the thread is added to the Java
+  // thread list in the Threads::add() method. That method is holding
+  // the Threads_lock which ensures we are outside a safepoint. We
+  // cannot do the obvious and set the active field of the SATB queue
+  // when the thread is created given that, in some cases, safepoints
+  // might happen between the JavaThread constructor being called and the
+  // thread being added to the Java thread list (an example of this is
+  // when the structure for the DestroyJavaVM thread is created).
+#ifndef SERIALGC
+  void initialize_queues();
+#else // !SERIALGC
+  void initialize_queues() { }
+#endif // !SERIALGC
+
   // Machine dependent stuff
   #include "incls/_thread_pd.hpp.incl"