--- src/client/messagepatterns/SimpleRpcServer.cs	Tue Feb 24 18:20:00 2009
+++ src/client/messagepatterns/SimpleRpcServer.cs	Tue Jun 09 17:48:53 2009
@@ -203,10 +203,14 @@
         public void MainLoop()
         {
             foreach (BasicDeliverEventArgs evt in m_subscription) {
-                ProcessRequest(evt);
-                m_subscription.Ack();
-                if (m_transactional) {
-                    m_subscription.Model.TxCommit();
+                lock(m_subscription){
+                    // if we don't have a valid consumer, we must be closing, so quit
+                    if(m_subscription.Consumer == null) break;
+                    ProcessRequest(evt);
+                    m_subscription.Ack();
+                    if (m_transactional) {
+                        m_subscription.Model.TxCommit();
+                    }
                 }
             }
         }
--- src/client/messagepatterns/Subscription.cs	Tue Feb 24 18:20:00 2009
+++ src/client/messagepatterns/Subscription.cs	Tue Jun 09 17:04:03 2009
@@ -218,22 +218,24 @@
         ///case).</summary>
         public void Close()
         {
-            try {
-                if (m_consumer != null) {
-                    m_model.BasicCancel(m_consumerTag);
+            lock(this){
+                try {
+                    if (m_consumer != null) {
+                        m_model.BasicCancel(m_consumerTag);
+                    }
+                    if (m_shouldDelete) {
+                        m_shouldDelete = false;
+                        // We set m_shouldDelete false before attempting
+                        // the delete, because trying twice is worse than
+                        // trying once and failing.
+                        m_model.QueueDelete(m_queueName, false, false, false);
+                    }
+                } catch (OperationInterruptedException) {
+                    // We don't mind, here.
                 }
-                if (m_shouldDelete) {
-                    m_shouldDelete = false;
-                    // We set m_shouldDelete false before attempting
-                    // the delete, because trying twice is worse than
-                    // trying once and failing.
-                    m_model.QueueDelete(m_queueName, false, false, false);
-                }
-            } catch (OperationInterruptedException) {
-                // We don't mind, here.
+                m_consumer = null;
+                m_consumerTag = null;
             }
-            m_consumer = null;
-            m_consumerTag = null;
         }
 
         ///<summary>Causes the queue to which we have subscribed to be