8217794: Missing termination check results violation of termination invariant

Reviewed-by: tschatzl, shade

src/hotspot/share/gc/shared/owstTaskTerminator.cpp

@@ -65,6 +65,13 @@ bool OWSTTaskTerminator::offer_termination(TerminatorTerminator* terminator) {
         return true;
       } else {
         _blocker->lock_without_safepoint_check();
+        // There is possibility that termination is reached between dropping the lock
+        // before returning from do_spin_master_work() and acquiring lock above.
+        if (_offered_termination == _n_threads) {
+          _blocker->unlock();
+          assert(!peek_in_queue_set(), "Precondition");
+          return true;
+        }
       }
     } else {
       _blocker->wait(true, WorkStealingSleepMillis);