[jira] [Updated] (AMQ-7232) Incorrect message counters when using virtual destinations

["Jean-Baptiste Onofré (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/AMQ-7232?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jean-Baptiste Onofré updated AMQ-7232:
--------------------------------------
    Fix Version/s:     (was: 5.16.2)
                   5.16.3

> Incorrect message counters when using virtual destinations
> ----------------------------------------------------------
>
>                 Key: AMQ-7232
>                 URL: https://issues.apache.org/jira/browse/AMQ-7232
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>            Reporter: Lionel Cons
>            Assignee: Jean-Baptiste Onofré
>            Priority: Major
>             Fix For: 5.16.3
>
>         Attachments: Virtual Destinations.jpg
>
>
> ActiveMQ supports [virtual destinations|https://activemq.apache.org/virtual-destinations] to magically link one or more queues to a topic.
> It also supports [JMX attributes|https://activemq.apache.org/jmx.html] to count messages going through the different destinations in a broker. There are both per-destination attributes ({{EnqueueCount}} and {{DequeueCount}}) and per-broker attributes ({{TotalEnqueueCount}} and {{TotalDequeueCount}}).
> Unfortunately, these two features do not work well together.
> Take for instance the following scenario:
>  * one topic ({{/topic/T}})
>  * two virtual queues attached to it({{/queue/Consumer.A.T}} and {{/queue/Consumer.B.T}})
>  * one topic producer ({{PT1}})
>  * two queue consumers on each virtual queue ({{CA1}}, {{CA2}}, {{CB1}} and {{CB2}})
> !Virtual Destinations.jpg!
> When sending a single message, we get:
>  * {{/topic/T}}: {{EnqueueCount += 1}} and {{DequeueCount += 0}}
>  * {{/queue/Consumer.A.T}}: {{EnqueueCount += 1}} and {{DequeueCount += 1}}
>  * {{/queue/Consumer.B.T}}: {{EnqueueCount += 1}} and {{DequeueCount += 1}}
>  * at broker level: {{TotalEnqueueCount += 3}} and {{TotalDequeueCount += 2}}
> This is not consistent: when the message leaves the topic to go to the virtual queues, {{DequeueCount}} (on the topic) does not change while {{EnqueueCount}} (on the queues) does change.
> At broker level, {{TotalEnqueueCount}} gets incremented too much, giving the impression that 3 messages have been received.
> The main question is: should the counters be incremented when a message is magically forwarded from the topic to the attached virtual queues?
> I would argue that these counters should *not* change when messages move internally (i.e. along dashed lines). This way, we can continue to have {{TotalEnqueueCount}} being the sum of all {{EnqueueCount}} and at the same time representing the number of messages received (globally) by the broker. Idem for {{TotalDequeueCount}} and {{DequeueCount}}.
> IMHO, these counters should only change when messages move along solid lines. If we want to track the internals (i.e. dashed lines) then we should have an additional counter, a bit like we already have {{ForwardCount}} for network of brokers.



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