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Posted to dev@qpid.apache.org by "Pavel Moravec (JIRA)" <ji...@apache.org> on 2014/07/25 08:34:38 UTC
[jira] [Commented] (QPID-5642) Message sequence numbers (enabled
with qpid.msg_sequence) should be persistent across broker restarts
[ https://issues.apache.org/jira/browse/QPID-5642?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14074137#comment-14074137 ]
Pavel Moravec commented on QPID-5642:
-------------------------------------
Review https://reviews.apache.org/r/19566/ pending on Alan's improvements to the replication sequence for newcomers brokers.
> Message sequence numbers (enabled with qpid.msg_sequence) should be persistent across broker restarts
> -----------------------------------------------------------------------------------------------------
>
> Key: QPID-5642
> URL: https://issues.apache.org/jira/browse/QPID-5642
> Project: Qpid
> Issue Type: Bug
> Components: C++ Broker
> Affects Versions: 0.26
> Reporter: Pavel Moravec
> Assignee: Pavel Moravec
> Priority: Minor
>
> The C++ broker supports currently only at-least-once and at-most-once reliability. Therefore duplicate messages may occur, especially in situations involving failovers, reconnects etc. Currently, the broker doesn't offer any specific solution for duplicate detection. For many messaging scenarios, it is crucial to process every message only once to avoid errors.
> The broker supports message sequencing on exchange level. The message sequencing assigns a sequence number to every message which is routed via the exchange. In theory, this can be used to detect duplicates. Unfortunately, the sequence number isn't stored persistently and is restarted with every restart of the broker (HA cluster) and starts again from 1. That makes the use of the sequence number for duplicate detection quite complicated, especially since the restart of the broker is also the situation when the duplicates may occur.
> Therefore, it is required to update message sequence numbers (enabled with qpid.msg_sequence) to store/journal after every (pre)route of a durable exchange, in order to persist the sequence numbers accross broker restart.
>
> Reproducer:
> rm -rf /var/lib/qpidd/* output.txt
> service qpidd restart
> qpid-config add exchange fanout myFanout --sequence --durable
> qpid-receive -a myFanout --connection-options="{reconnect:true}" -f --print-content=no --print-header=yes -m 6 > output.txt 2>/dev/null &
> sleep 1
> qpid-send -a myFanout -m 3
> service qpidd restart
> sleep 1
> qpid-send -a myFanout -m 3
> cat output.txt
> Current output:
> Properties: {qpid.msg_sequence:1, sn:1, ts:1394611002529779545, x-amqp-0-10.routing-key:}
> Properties: {qpid.msg_sequence:2, sn:2, ts:1394611002529879589, x-amqp-0-10.routing-key:}
> Properties: {qpid.msg_sequence:3, sn:3, ts:1394611002529896423, x-amqp-0-10.routing-key:}
> Properties: {qpid.msg_sequence:1, sn:1, ts:1394611004142278196, x-amqp-0-10.routing-key:}
> Properties: {qpid.msg_sequence:2, sn:2, ts:1394611004142340093, x-amqp-0-10.routing-key:}
> Properties: {qpid.msg_sequence:3, sn:3, ts:1394611004142354743, x-amqp-0-10.routing-key:}
> Expected output:
> Properties: {qpid.msg_sequence:1, sn:1, ts:1394611002529779545, x-amqp-0-10.routing-key:}
> Properties: {qpid.msg_sequence:2, sn:2, ts:1394611002529879589, x-amqp-0-10.routing-key:}
> Properties: {qpid.msg_sequence:3, sn:3, ts:1394611002529896423, x-amqp-0-10.routing-key:}
> Properties: {qpid.msg_sequence:4, sn:1, ts:1394611004142278196, x-amqp-0-10.routing-key:}
> Properties: {qpid.msg_sequence:5, sn:2, ts:1394611004142340093, x-amqp-0-10.routing-key:}
> Properties: {qpid.msg_sequence:6, sn:3, ts:1394611004142354743, x-amqp-0-10.routing-key:}
> (sn comes from qpid-send so it will be re-set to 1)
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