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https://issues.apache.org/jira/browse/QPID-601?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Aidan Skinner updated QPID-601:
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Component/s: Java Broker
Assignee: Rob Godfrey
Rob, I think this has been fixed / invalidated by your refactoring, is that
true?
> messages may be stranded when selectors are used
> ------------------------------------------------
>
> Key: QPID-601
> URL: https://issues.apache.org/jira/browse/QPID-601
> Project: Qpid
> Issue Type: Bug
> Components: Java Broker
> Affects Versions: M2, M2.1, M3
> Reporter: Rafael H. Schloming
> Assignee: Rob Godfrey
>
> ConcurrentSelectorDeliveryManager = CSDM
> PDQ = PreDeliveryQueue
> pPDQ = populatePreDeliveryQueue
> Messages may be stranded as a result of the way selectors are implemented.
> When a consumer subscribes to a queue using a filter, CSDM.pPDQ is called to
> move messages from CSDM._messages into the PDQ for that subscription. The
> pPDQ method does this by calling _messages.iterator() and placing matching
> messages into the PDQ of the subscription. The result of _messages.iterator()
> is not guaranteed to reflect concurrent changes made to _messages, and so a
> publish may end up causing a message that matches the subscription to be
> placed onto _messages. This message is then stranded there despite the fact
> that the subscription could accept the message because nothing ever
> reexamines the _messages queue after the initial pPDQ when the consumer
> subscribes.
> One potential fix for this issue would be to make the pPDQ method block
> messages from being pushed onto the _messages queue while it operates. This
> would work, however it would introduce undesirable synchronization for all
> publishers attempting to place messages on the queue.
> So far I can't think of a proper fix for this issue that doesn't involve some
> substantial changes in the data structures for queuing and delivering
> messages.
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