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From djdkedev <djte...@gmail.com>
Subject Redelivery counter is not getting incremented when LastDeliveredSeqID > BrokerSequenceId
Date Thu, 03 Oct 2019 00:26:16 GMT
ssue: Redelivery counter is not getting incremented when LastDeliveredSeqID >
BrokerSequenceId

Version tested : ActiveMQ 5.14.4 and 5.15.10 versions

Description:
I have created the two queues, one for sending requests and other for
receiving its response.
The steps for these queues are given below.

Steps:

1. SenderA (Machine A) sends Msg on RequestQueue TO ReceiverB (Machine B)
(Redelivery count is 0, Ack Mode:INDIVIDUAL_ACKNOWLEDGE).

2. SenderB sends ResponseMsg on Response queue (Machine B) TO ReceiverA
(Machine A) (Async Msg Listener, Ack Mode:CLIENT_ACKNOWLEDGE)

3. SenderB is waiting for the consumed advisory for ResponseMsg. Request Msg
is not yet acknowledged.

4. ReceiverA acknowledges the ResponseMsg. ResponseMsg consumed advisory is
received by SenderB

5. Machine B disconnects from the embedded broker hosted on Machine A

6. On Machine B reconnection, Broker sends Msg on RequestQueue again ->
ReceiverB (Issue: Redelivery count is 0 instead of 1)

Analysis:
1. The Queue.java has removeSubscription() function which increments the
redelivery counter by comparing lastDeliveredSequenceId and
BrokerSequenceId.
2. The step4 incremented the LastDeliveredSeqID for message consumed
advisory.
3. The transport connection updates the lastDeliveredSequenceId for each
consumer by calling
processRemoveConsumer(consumerId, lastDeliveredSequenceId);
4. The condition “ref.getMessageId().getBrokerSequenceId() ==
lastDeliveredSequenceId” in removeSubscription() doesn’t set
markAsRedelivered to true.

org.apache.activemq.broker.region.Queue removeSubscription
FINE: queue://RequestQueue_334 remove sub: QueueSubscription:
consumer=ID:5107-1569853470047-1:1:1:1, destinations=1, dispatched=2,
delivered=2, pending=0, prefetch=1, prefetchExtension=2, lastDeliveredSeqId:
17, dequeues: 0, dispatched: 2, inflight: 2, groups: 0
org.apache.activemq.broker.region.Queue removeSubscription
FINE: LastDeliveredSeqID: 17, message reference:
ID:WIN2K8R2-7986-1569853472713-4:1:1:1:1, BrokerSequenceId 7
org.apache.activemq.broker.region.Queue removeSubscription
FINE: LastDeliveredSeqID: 17, message reference:
ID:WIN2K8R2-7986-1569853472713-4:1:1:1:2, BrokerSequenceId 8

Queue.java , removeSubscription()

Existing Code in 5.14.4:

// locate last redelivered in unconsumed list (list in delivery rather than
seq order)
if (lastDeliveredSequenceId > RemoveInfo.LAST_DELIVERED_UNSET) {
for (MessageReference ref : unAckedMessages) {
if (ref.getMessageId().getBrokerSequenceId() == lastDeliveredSequenceId) {
lastDeliveredRef = ref;
markAsRedelivered = true;
LOG.debug("found lastDeliveredSeqID: {}, message reference: {}",
lastDeliveredSequenceId, ref.getMessageId());
break;
}
}
}

Suggested fix:

// locate last redelivered in unconsumed list (list in delivery rather than
seq order)
if (lastDeliveredSequenceId > RemoveInfo.LAST_DELIVERED_UNSET) {
for (MessageReference ref : unAckedMessages) {
LOG.debug("UnAcked message reference: {}, BrokerSequenceId {}",
ref.getMessageId(), ref.getMessageId().getBrokerSequenceId());
if (lastDeliveredSequenceId == 0 || (lastDeliveredSequenceId > 0 &&
ref.getMessageId().getBrokerSequenceId() <= lastDeliveredSequenceId))
{
lastDeliveredRef = ref;
markAsRedelivered = true;
LOG.debug("found lastDeliveredSeqID: {}, message reference: {}",
lastDeliveredSequenceId, ref.getMessageId());
}
}
}

Could you please review the analysis and fix?

Thanks,
Dhananjay



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