--- 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"