1 files changed, 22 insertions, 4 deletions

diff --git a/cpp/src/qpid/broker/Queue.cpp b/cpp/src/qpid/broker/Queue.cpp
index 40ef6052a0..e59857462c 100644
--- a/cpp/src/qpid/broker/Queue.cpp
+++ b/cpp/src/qpid/broker/Queue.cpp
@@ -494,16 +494,34 @@ void Queue::purgeExpired()
 {
     //As expired messages are discarded during dequeue also, only
     //bother explicitly expiring if the rate of dequeues since last
-    //attempt is less than one per second.
-    if (dequeueTracker.sampleRatePerSecond() < 1) {
+    //attempt is less than one per second.  
+
+    //Note: This method is currently called periodically on the timer
+    //thread. In a clustered broker this means that the purging does
+    //not occur on the cluster event dispatch thread and consequently
+    //that is not totally ordered w.r.t other events (including
+    //publication of messages). However the cluster does ensure that
+    //the actual expiration of messages (as distinct from the removing
+    //of those expired messages from the queue) *is* consistently
+    //ordered w.r.t. cluster events. This means that delivery of
+    //messages is in general consistent across the cluster inspite of
+    //any non-determinism in the triggering of a purge. However at
+    //present purging a last value queue could potentially cause
+    //inconsistencies in the cluster (as the order w.r.t publications
+    //can affect the order in which messages appear in the
+    //queue). Consequently periodic purging of an LVQ is not enabled
+    //(expired messages will be removed on delivery and consolidated
+    //by key as part of normal LVQ operation).
+
+    if (dequeueTracker.sampleRatePerSecond() < 1 && !lastValueQueue) {
         Messages expired;
         {
             Mutex::ScopedLock locker(messageLock);
             for (Messages::iterator i = messages.begin(); i != messages.end();) {
-                if (lastValueQueue) checkLvqReplace(*i);
+                //Re-introduce management of LVQ-specific state here
+                //if purging is renabled for that case (see note above)
                 if (i->payload->hasExpired()) {
                     expired.push_back(*i);
-                    clearLVQIndex(*i);
                     i = messages.erase(i);
                 } else {
                     ++i;