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From "Gary Tully (JIRA)" <j...@apache.org>
Subject [jira] [Created] (AMQ-5266) Stuck Messages in Single Broker when using JDBC Persistent Store
Date Wed, 09 Jul 2014 16:05:04 GMT
Gary Tully created AMQ-5266:
-------------------------------

             Summary: Stuck Messages in Single Broker when using JDBC Persistent Store
                 Key: AMQ-5266
                 URL: https://issues.apache.org/jira/browse/AMQ-5266
             Project: ActiveMQ
          Issue Type: Bug
          Components: Message Store
    Affects Versions: 5.10.0
            Reporter: Gary Tully
            Assignee: Gary Tully
             Fix For: 5.11.0


With multiple concurrent producer transactions and active fast consumers it is possible to
get out of order db insertions and scans resulting in a skipped dispatch. This scenario is
exacerbated when the cursor cache is disabled because every dispatch will potentially result
in a scan.
the JDBC store maps jms transaction to jdbc connection transactions at the point of a commit
and these can occur in parallel. The broker tracks a sequenceId to ensure ordering relative
to a jms connection and  scans respect that order but there is currently nothing to stop a
scan seeing a later sequence before an earlier sequence is stored. In other words, inserts
can race, but the reader needs to limit a read to the lowest outstanding sequence.

On a restart, any stuck messages will be replayed correctly, because the cursor transient
state w.r.t to the last sequence id read will be reset.



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