1490   // This method initializes the SATB and dirty card queues before a

  1491   // JavaThread is added to the Java thread list. Right now, we don't

  1492   // have to do anything to the dirty card queue (it should have been

  1493   // activated when the thread was created), but we have to activate

  1494   // the SATB queue if the thread is created while a marking cycle is

  1495   // in progress. The activation / de-activation of the SATB queues at

  1496   // the beginning / end of a marking cycle is done during safepoints

  1497   // so we have to make sure this method is called outside one to be

  1498   // able to safely read the active field of the SATB queue set. Right

  1499   // now, it is called just before the thread is added to the Java

  1500   // thread list in the Threads::add() method. That method is holding

  1501   // the Threads_lock which ensures we are outside a safepoint. We

  1502   // cannot do the obvious and set the active field of the SATB queue

  1503   // when the thread is created given that, in some cases, safepoints

  1504   // might happen between the JavaThread constructor being called and the

  1505   // thread being added to the Java thread list (an example of this is

  1506   // when the structure for the DestroyJavaVM thread is created).

  1507 #ifndef SERIALGC

  1508   void initialize_queues();

  1509 #else // !SERIALGC

  1510   void initialize_queues() { }

  1511 #endif // !SERIALGC

  1512