[jira] [Created] (AMQ-6286) Queue order lost on repeated redelivery

["Gary Tully (JIRA)" <ji...@apache.org>]

Gary Tully created AMQ-6286:
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             Summary: Queue order lost on repeated redelivery
                 Key: AMQ-6286
                 URL: https://issues.apache.org/jira/browse/AMQ-6286
             Project: ActiveMQ
          Issue Type: Bug
          Components: Broker
    Affects Versions: 5.13.0
            Reporter: Gary Tully
            Assignee: Gary Tully
             Fix For: 5.14.0


When a consumer prefetches messages or consumes and does not ack in pull mode, on close, any messages that have not been acked end up in on the broker in the already delivered list.
These messages get dispatched first. However, if these messages are unconsumed again, they get appended to the dispatched list.
This makes sense when there are multiple consumers, A gets 10, B gets 10, A closes, there are 10 to redeliver, B closes, there are now 20 to redeliver. the order should be preserved.
However if there is a single consumer this breaks.

Consider: 
publish 100 to Q
consume 50 and rollback/close with all unacked, expect 0-49
consume 10 and rollback/close with all unacked, expect 0-9
consume 10 more ... expect 0-9 but get 10-19!

In concert with the strictOrderDispatch policy, I think we should be able to support the natural expectation here.

The scenario presents its self with prefetched messages where the prefetch varies or more naturally with a single consumer that consumed in various transaction batches. In the transacted case, two failures would result in compromised queue ordering. 





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