diff -r bb18957ad21e -r df6caf649ff7 src/share/vm/utilities/taskqueue.cpp
--- a/src/share/vm/utilities/taskqueue.cpp	Fri Jul 10 16:01:20 2009 -0700
+++ b/src/share/vm/utilities/taskqueue.cpp	Tue Jul 14 15:40:39 2009 -0700
@@ -64,15 +64,18 @@
 }
 
 void ParallelTaskTerminator::yield() {
+  assert(_offered_termination <= _n_threads, "Invariant");
   os::yield();
 }
 
 void ParallelTaskTerminator::sleep(uint millis) {
+  assert(_offered_termination <= _n_threads, "Invariant");
   os::sleep(Thread::current(), millis, false);
 }
 
 bool
 ParallelTaskTerminator::offer_termination(TerminatorTerminator* terminator) {
+  assert(_offered_termination < _n_threads, "Invariant");
   Atomic::inc(&_offered_termination);
 
   uint yield_count = 0;
@@ -96,6 +99,7 @@
   // Loop waiting for all threads to offer termination or
   // more work.
   while (true) {
+    assert(_offered_termination <= _n_threads, "Invariant");
     // Are all threads offering termination?
     if (_offered_termination == _n_threads) {
       return true;
@@ -151,6 +155,7 @@
       if (peek_in_queue_set() ||
           (terminator != NULL && terminator->should_exit_termination())) {
         Atomic::dec(&_offered_termination);
+        assert(_offered_termination < _n_threads, "Invariant");
         return false;
       }
     }