Hi amq devs,
I know that this is basically a user type configuration question and the very
first thing a colleague of mine was doing after checking all available
documentation on ActiveMQ regarding this topic was posting a question to the
user list [1].
As there is so far no reply and I invested quite some minutes digging through
the source code, I'd like to ask some code/design related questions which are
hopefully on topic and whose answers will help us to overcome our current
problems.
We use a SpringMessageListenerContainer and configured the used connection
factory with the redelivery policy we like to use. As the code in this area
does not contain any debug or trace logs, we debugged the ActiveMQ code around:
org.apache.activemq.ActiveMQMessageConsumer#rollback
were we can find this code handling the redelivery logic:
MessageDispatch lastMd = deliveredMessages.getFirst();
final int currentRedeliveryCount = lastMd.getMessage().getRedeliveryCounter();
if (currentRedeliveryCount > 0) {
redeliveryDelay = redeliveryPolicy.getNextRedeliveryDelay(redeliveryDelay);
} else {
redeliveryDelay = redeliveryPolicy.getInitialRedeliveryDelay();
}
At this point we could also easily validate that all our properties provided on
the factory were correctly propagated to the ActiveMQConnection
(initialRedeliveryDelay, backOffMultiplier, maximumRedeliveryDelay, etc.) and
redelivery actually works, but not using the correct redelivery delay.
We can also see why the redeliveryDelay does not increase with each retry
attempt as expected/configured. Each time the breakpoint is hit a new consumer
instance is used, so the redeliveryDelay (member of the consumer is "reset" to
zero al the time).
What I did not get is why this property is no provider specific property on the
message alongside the redeliveryCounter, but rather stored with a consumer
instance?
Is it expected that the consumer instance will not change? Is this a major
limitation of the current implementation or do I simply did not get the idea
behind the implementation as I'm completely new to the code?
What if there are multiple listeners even on different machines? How to share
the current redelivery delay if this information is not designed as meta data
of the message?
Many thanks for anyone who is able and willing to shed some light on this.
Please also respond if this is indeed a bug or at least a limitation which
should be removed! As this is currently a blocker for us to move on with
ActiveMQ we would be willing to support and look deeper into the code and check
whether we can be able to support/come up with some improvement ideas and/or a
patch.
Side questions out of interest:
Are you guys currently more actively working on the next v5 maintenance release
(5.6) or towards the next major (6.0)? Looking at both trunk and Jira all
speaks for 5.6. Is Apollo intended to become "the ActiveMQ 6" or the successor
at some point? Looking at the commits of Apollo I got the first impression
Hiram is currently working more or less alone on the Apollo code base.
Regards,
Eric
[1]
http://activemq.2283324.n4.nabble.com/RedeliveryPolicy-not-working-with-Springs-DefaultMessageListenerContainer-td4039575.html
