[jira] Reopened: (QPID-1488) QueuePolicy serialization fix for cluster braindump.

["Gordon Sim (JIRA)" <qp...@incubator.apache.org>]

     [ https://issues.apache.org/jira/browse/QPID-1488?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gordon Sim reopened QPID-1488:
------------------------------

      Assignee: Alan Conway

I believe this fix is wrong. The messages on a queue are replicated to the joining member and as part of that the policy will be updated. The only part missing is those messages in the unacked state as these are transferred separately, are not pushed onto the delivery queue and thus not reflected in the computed policy count.

As it stands I believe (a) the policy count may well be incorrect on the new replica as enqueued messages will be counted twice, (b) more seriously, the root issue opens the potential for unacked durable messages to be dequeued without being enqueued first on a new replica.


> QueuePolicy serialization fix for cluster braindump.
> ----------------------------------------------------
>
>                 Key: QPID-1488
>                 URL: https://issues.apache.org/jira/browse/QPID-1488
>             Project: Qpid
>          Issue Type: Improvement
>          Components: C++ Broker
>         Environment: tested on F9
>            Reporter: michael j. goulish
>            Assignee: Alan Conway
>            Priority: Blocker
>         Attachments: queue_policy_serialization_bug.diff
>
>
> In cluster braindump (when a new member is being added to a cluster) the QueuePolicy is not being serialized out as part of the brain dump.  As a result the newbie cluster can get a mistaken idea of the queue size (in bytes).  
> After many dequeues, the size can go negative, but since the queue size is an unsigned number it wraps around and look like a large positive.  Which sets off the flow-to-disk code, because it thinks that the queue has gotten too large.
> The result:    what():  framing-error: Unexpected command start frame. (qpid/SessionState.cpp:57)
> This fix just adds a little serialization of the QueuePolicy on to the end of the serialization of the Queue.

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